Glossary

Plain-language definitions of the terms product managers, marketers and founders meet in dashboards, A/B tests, interviews, roadmaps and finance.

0

0/1 variable (dummy variable): An input that is either 1 (a condition holds) or 0 (it does not). In ŷ = b₀ + b₁x + b₂·d its coefficient b₂ shifts the prediction when d = 1.

1

100% rule: A work breakdown must include all of the work in scope and nothing outside it.

3

30-60-90 day plan: A one-page plan for the first three months in a new role: first learn and listen, then fix a few visible problems, then set direction. Each stage has two or three concrete outcomes you can check.
30-day prior price rule: The EU rule that an announced price reduction must be measured from the lowest price the seller charged in the 30 days before it, so a briefly raised price cannot inflate a discount (as of October 2026). The rule itself covers goods; for services such as lessons, a fake reference price falls under the general ban on misleading prices, and the course uses the 30-day lowest price as the honest default for both.

6

68–95–99.7 rule: For a normal curve, about 68% of values lie within 1 SD of the mean, 95% within 2 SD (exactly ±1.96) and 99.7% within 3 SD.

A

A/B test: A randomised controlled experiment that splits users between a control (A) and one or more variants (B) and compares a metric.
AARRR funnel (pirate metrics): A five-stage framework for the customer lifecycle: Acquisition, Activation, Retention, Referral and Revenue, with one or two metrics per stage to find where growth leaks.
ability to win: How well you can serve a segment better than its alternatives: the fit of your offer, what you can prove, your reach into it and your costs. A huge segment you can't win is not a target.
absolute change: The new value minus the old one, in the units of the number itself. When both values are percentages, the absolute change is in percentage points.
acceptance criteria: Checkable conditions agreed in advance that a specific deliverable must meet before someone accepts it. "Good lessons" is a wish; "every topic has a worked example and ten graded practice tasks" is a criterion.
account scoring: Ranking target companies or segments by a few weighted criteria that predict a good deal, such as fit, need, reachability and expected profit. Each criterion needs a clear direction (higher is better or worse) and profit, not revenue, should carry the weight.
account tier: A group of target accounts that get the same depth of attention: a few key accounts handled one-to-one, a cluster of similar ones handled one-to-few, and the rest handled one-to-many. Tiers keep expensive personal work for the accounts that can repay it.
account-based marketing (ABM): An approach in which marketing and sales pick specific target companies first and then shape messages, content and outreach for the people in those companies, instead of attracting as many leads as possible and sorting them later.
accounts payable: Money the company owes suppliers or providers for what it has already received, such as tutor payouts due at the next payout date.
accounts receivable: Money customers owe for what has already been delivered and invoiced, such as a company that pays for corporate lessons 60 days after the invoice.
accrual accounting: Recording revenue when it is earned and costs when they are incurred, whatever the date money moves. The P&L is built this way; the bank statement isn't.
accumulating fund: A fund that reinvests dividends inside the fund instead of paying them out.
acqui-hire: An acquisition made mainly to hire the company's team, not to keep its product or customers. The product is often shut down, and most of the value goes to the people through job offers rather than to the owners through the price.
action item: A step agreed in a meeting, written down with one owner, the concrete next step and a date. Without all three, a meeting tends to end in shared good intentions that nobody carries out.
activation: The moment a new user first gets the product's core value, defined by a specific action within a specific time, such as 'added an expense with at least one other member within 3 days'.
active investing: Trying to beat a market by choosing which securities to hold or when to trade.
active sales: Proactive selling to customers outside the partner's own territory or group; distinct from passive sales answering unsolicited requests.
actively managed fund: A fund whose managers pick what to buy and sell, trying to beat an index; it usually charges a higher yearly fee than an index fund.
actual cost: What has really been spent on the work done so far.
adding in quadrature: Combining independent errors as the sides of a right triangle: √(a² + b²). SEs of 0.6 and 0.8 pp give an SE of the difference of 1.0 pp, not 1.4.
advancement: The customer moving to the next concrete step of your buying or sales process, such as a follow-up with goals, an intro or a trial.
after hours: Time outside the regular session when fewer people trade, so spreads are wider and prices jump more.
after-tax rate: What a rate leaves once tax on the interest is paid: r × (1 − t). 14% with 23% tax is 10.78%. The reverse, r ÷ (1 − t), gives the taxed rate that matches a tax-free one.
aha moment: The first moment a new user clearly sees the product's value, such as a shop owner seeing a forgotten regular come back after a reminder. Users who reach it early are far more likely to stay and pay, so onboarding is built to get them there fast.
all-in cost: Every cost of owning an investment added together: fund fee, spread, FX, platform and tax drag.
alternative hypothesis (H1): The claim accepted when H0 is rejected: there is a difference or effect.
always-on marketing: Marketing that runs all year at a steady level (search, your site, a regular newsletter) so customers find you whenever they look, as opposed to campaigns that run for a few weeks around a moment.
amortization: Repaying a loan in installments, each covering that month’s interest first and repaying principal with the rest: B(t+1) = B(t) × (1 + r) − payment. With equal payments the interest part shrinks and the principal part grows.
analysis of variance (ANOVA): Tests whether the means of three or more groups differ by comparing between-group and within-group variance.
anchoring fluff: Turning a vague answer into a concrete one by asking about a specific past instance, e.g. "When did that last happen? Walk me through it."
annual plan: A subscription paid a year in advance, usually at a discount to twelve monthly payments. It brings cash early, cuts the number of moments when a customer can cancel, and signals strong commitment.
annuity factor: The present value of a series of equal payments of 1: the sum of their discount factors. Five yearly payments at 25%: 0.8 + 0.64 + 0.512 + 0.4096 + 0.32768 = 2.68928.
approve: A review verdict that says the changes are fine to merge. Shown as `Approved` with a green check.
ARPA (average revenue per account): MRR divided by the number of paying accounts (customers): how much an average customer pays per month. In B2B products one account often has several users, so ARPA is used instead of revenue per user.
ARPPU: Average revenue per paying user: revenue divided by paying users only. It can rise while total revenue falls.
ARPU: Average revenue per user: revenue in a period divided by all active users, paying or not. Compare with ARPPU.
ARR (annual recurring revenue): Recurring subscription revenue expressed per year, usually MRR × 12. Buyers and investors often quote company value as a multiple of ARR.
ask: The lowest price someone is willing to sell at right now; it is the price you pay if you buy immediately.
ask for advice, not a favour: Going into a conversation as if you were assessing whether the person could be a good advisor rather than trying to sell to them; it keeps you in control and out of pitch mode.
asset allocation: How a portfolio is split between stocks, bonds and cash; the choice that shapes most of its risk and return.
assumption: Something the plan treats as true without having checked it yet, such as enough tutors being free in January. Each assumption gets a date by which it is checked; one that turns out false becomes an issue or a change to the plan.
asynchronous communication: Work communication that doesn't need people to be present at the same time: written updates, comments, recorded explanations. It suits teams across time zones and outages, and works when messages are complete enough to act on without a follow-up call.
attribution: Giving credit for a sale to the touchpoints before it: the last click, a "how did you hear about us?" answer, a promo code. Attribution reports are clues, not proof of what marketing caused.
attribution: Assigning credit for a new user or purchase to a channel or campaign. On mobile it now relies on privacy-preserving store frameworks with aggregated, delayed data.
automatic renewal: A subscription that renews and charges again unless the customer cancels; honest practice states the renewal price and date up front, reminds before charging and makes cancelling as easy as signing up.
autonomy at work: How much say a person has over how, when and in what order they do their work. More autonomy tends to raise motivation and learning, but only together with clear goals and the skill to use it.
average daily range: The usual distance between a day's high and low, averaged over recent days; a handy yardstick for how wide a stop should be.
average order value (AOV): Revenue divided by the number of orders; usually right-skewed, so outliers matter.

B

B2B content marketing: Creating material that helps the people on a buying committee understand their problem, compare options and justify a purchase internally: guides, calculators, case studies, checklists for security or procurement. Its test is whether a buyer uses it in a real decision, not how many views it gets.
back-of-the-envelope estimate: A quick estimate from a short chain of round numbers you can defend, done in your head or on scrap paper. Its job is to get the order of magnitude right, not the exact value.
backtest: Running a rule on past prices to see how it would have done; useful, but easy to fool yourself with.
bad data: Anything from a conversation that feels like evidence but isn't: compliments, fluff (generic, future and hypothetical answers) and unexamined ideas or feature requests.
balance sheet: A snapshot at one date of what the company has (assets) and how it is financed (liabilities and equity). The two sides are always equal.
band rebalancing: Rebalancing only when an asset’s share moves more than a set number of points from its target, for example 5, instead of on a fixed date.
bar chart: A chart comparing counts or values across categories with separate bars.
base (of a percent): The number a percent is taken of: the value you divide by. In a change from b to a, the base is the old value b; change the base and the same gap gives a different percent.
baseline: What would have happened without the campaign: last year's figures for the same period, the trend, customers who return every season anyway. Marketing's effect is the difference from the baseline, not the total.
baseline (in marketing measurement): What a metric such as leads, deals or margin would have been without the campaign, estimated from history, a comparable period or a control group that did not get the campaign. Only the difference above the baseline can be credited to marketing.
baseline rate: The current value of the metric in control; an input to sample-size calculations.
basis point: One hundredth of a percent: 100 basis points make 1%. Used to compare small changes without confusion between percent and percentage points.
Bayesian statistics: An approach that combines prior beliefs with new data (Bayes' theorem) to get updated, posterior probabilities.
behavior gap: The difference between a fund's return and the average return its investors actually got, caused by when they bought and sold.
behavioral segmentation: Grouping customers by what they actually do: when they start, how often they come, how long they stay and how much they buy. Built from your own records, it often splits an "average customer" into groups that need different treatment.
benchmark: The index a fund is compared with to judge whether it did better or worse than simply holding the market.
benefits check: A review a few weeks or months after the launch that compares the real outcome with the success criteria in the brief, such as bookings, not just whether things shipped on time. It decides what to fix, keep or stop, and feeds the next project's estimates.
between-group variance: The part of total variability explained by differences between group means.
bid: The highest price someone is willing to pay right now; it is the price you get if you sell immediately.
bid-ask spread: The gap between the price you can buy at and the price you can sell at; a cost paid on every trade.
blame: A GitHub file view that shows, next to every line, the last commit that changed it: who, when and with what message. It finds the source of a line, not a culprit.
blind spot: A habit or effect of your own behavior that others see and you don't. Because reports rarely volunteer it to their manager, a lead has to ask for it directly and make it safe to answer.
bond: A loan to a government or company that pays interest and returns the amount lent at a set date.
bond yield: The yearly return a bond pays if bought at today's price and held to maturity.
Bonferroni correction: Divide alpha by the number of comparisons, e.g. 0.05 / 3 = 0.017 for three tests.
bootstrapping: Building a business with little or no outside money: the founders' own savings and, as soon as possible, revenue from customers pay for everything. It is also a mindset of spending carefully and growing at a pace the business can afford.
boring technology: Well-known, mature, widely used tools that the team already knows. They carry fewer surprises than new, fashionable ones, which matters when the business itself is already a risk.
bottom-up market sizing: Estimating a market by counting real, nameable potential customers (from maps, directories, supplier lists, your own sales route), keeping only those who fit, and multiplying by your real price. The opposite of starting from an industry total and taking a percentage.
box plot (box-and-whisker plot): A chart showing the median, the IQR as a box, whiskers for the bulk of the data and dots for outliers.
bracket retention: The share of a cohort active at least once within a window, such as days 7–13 or week 4. Fits products used weekly or monthly.
branch: A named, movable line of commits: a parallel version of the project where work happens without touching the main branch.
break-even CAC: The most you can pay per acquired user and still earn it back within a stated horizon. If you count the users they invite, add their value as measured, not assumed: 12-month LTV + invitees per paid user × the invited users' own 12-month LTV. Check the invite credit with a holdout before bidding on it.
break-even conversion: After a price rise of x, the lowest conversion (current ÷ (1 + x)) at which revenue per viewer doesn't fall, if the plan mix stays the same.
break-even exchange rate: The future exchange rate at which saving in two currencies comes out equal: today’s rate × (1 + r_home) ÷ (1 + r_foreign). At 41.5 UAH per dollar, 10.78% in hryvnias and 1.5% in dollars, it is about 45.29.
break-even move: How far the price must move in your favour just to pay the costs of the trade; below it, even a right call loses money.
break-even point: The level of sales at which revenue exactly covers all costs, so the business neither loses nor makes money. For a subscription product it is usually expressed as a number of paying customers: fixed costs ÷ (revenue per customer − variable cost per customer).
break-even win rate: The share of winning trades a plan needs just to break even; the larger the average win compared with the average loss, the lower it can be.
breakage: The part of prepaid lessons or credits that customers never use. It becomes revenue only when the company can reliably expect it or when the right to use it expires.
breakout: A move of price beyond a support or resistance level, which may continue or may fail.
broker: The company whose app or platform you use to send orders to a market and which holds your account.
bubble: A stretch when prices rise far above what the underlying income can justify, followed by a sharp fall.
bubble chart: A scatter plot where point size encodes a third variable.
budget: The plan of revenue, costs and cash a team commits to for a period, used to allocate money and to judge results against.
budget slack: Deliberately low revenue or high cost estimates that make a budget easy to beat. It hides real performance and wastes money.
buffer account: An account where all irregular income lands and from which a fixed monthly salary is paid, so good months fund thin ones.
build vs buy: The decision whether to write a part of the product yourself or pay for a ready-made service. Parts that are not the core of the product, such as login, payments or invoicing, are usually safer to buy.
build, buy or hire: The project's choice for each piece of work: do it with the team, buy something ready, or hire a contractor or freelancer. The answer depends on how core the piece is, how clear its scope is and who will maintain it after the launch.
built-in quality: Quality checked while the work is done, in small pieces and against the acceptance criteria, instead of one big inspection at the end. A curriculum reviewed module by module surfaces problems while they are still cheap to fix.
burn rate: The amount of money a business or founder spends per month. Net burn subtracts the monthly revenue, and it is the number that decides how long the runway lasts.
burnout: A state that builds up from chronic work stress that hasn't been managed: exhaustion, growing distance or cynicism about the work, and a sense of doing it less well. A lead can change workload, control and recognition, but should point the person to a health professional rather than diagnose.
bus factor: The number of people who would have to be suddenly unavailable before a piece of work stops. A bus factor of one, often the lead, is a risk to fix with documentation, pairing and rotating responsibilities.
business case: A short, numbers-backed argument for a decision: the options, the cash flows of each, the key assumptions, the risks and a recommendation.
business objective: A goal the organization wants the product to achieve, such as growing recurring revenue, entering a new market or lowering the cost to serve. Every theme on an outcome-based roadmap should support at least one.
buy stop: A stop order placed above the price that turns into a buy once the price reaches it, often used to enter on a breakout.
buy-in: Stakeholders' active commitment to the roadmap because they understand its reasoning and had a chance to shape it, as opposed to grudging acceptance of a plan handed to them.
buyer payback period: How many months a buyer needs before the gains from a purchase cover what it cost them. ROI says how much comes back in total, payback says how soon; a finance director short on cash often cares more about the second.
buyer's risk: What a person on the buying side could lose if the purchase goes wrong: money, time, a project, or their own reputation inside the company. B2B sellers win by lowering that risk with proof, pilots, references and guarantees, not by talking louder about features.
buying committee: The group of people inside a company who influence or approve a purchase: the users, a champion, the budget owner, procurement, legal and IT security. Each of them can stop the deal, and each is guarding against a different risk.
buying situation: The kind of purchase a company is making: buying something for the first time, renewing or extending what it already uses, or switching from another supplier. The situation decides how many people get involved, how long it takes and what proof they need.

C

CAC: Customer acquisition cost: marketing spend divided by the new users (or paying customers) it brought. State which of the two you mean.
CAC (customer acquisition cost): What it costs on average to win one new paying customer: sales and marketing spending for a period ÷ new customers in that period. A healthy business earns back CAC well within the customer's lifetime.
CAC payback period: How many months of gross profit from a new customer it takes to earn back what it cost to acquire them: CAC ÷ (monthly revenue per customer × gross margin).
CAGR (compound annual growth rate): The steady yearly growth that turns a start value into an end value over n years: (end ÷ start)^(1/n) − 1. 100,000 → 275,589 over 20 years is a CAGR of 5.2%.
calendar audit: Sorting a lead's hours into doing, enabling the team and overhead, to see where time goes and what to hand over.
candle body and wick: The body is the distance between a candle's open and close; the thin wicks above and below show the high and the low of the period.
candlestick: A bar that shows the open, high, low and close of one period, coloured by whether the price rose or fell.
cannibalization: Sales of a new product or format that only replace sales of an existing one. Its value to the business is the new contribution minus the contribution of the sales it replaces.
cannibalization: When a new offer takes sales from your existing ones instead of bringing new customers. It is judged on total contribution across the range: a cheaper offer that only moves current customers down can lose money overall.
cap table: Short for capitalization table: a list of who owns what share of a company (founders, investors, employees with options), and how that changes with each investment, grant or sale.
capital expenditure (capex): Spending on assets that serve for years, such as equipment or a platform built in-house. It hits cash at once but reaches the P&L gradually through depreciation or amortization.
cash commitment: Putting money or a formal promise of money on the table: a letter of intent, a pre-order or a deposit.
cash conversion cycle: The days between paying for what you deliver and getting paid for it. A negative cycle means customers finance the business.
cash flow: The money actually coming into and going out of the business in a period. It differs from revenue and profit because payments arrive and leave at different times: an annual plan brings a year of cash at once, while the revenue is earned month by month.
cash flow statement: The report of cash in and out over a period, split into operating, investing and financing flows. It links the P&L to the change in the bank balance.
cash gap: A period when planned payments exceed the cash available, even if the business is profitable over the year.
cash plan: A month-by-month forecast of cash in, cash out and the closing balance, with the real timing of payments. It shows a cash gap before it happens.
categorical variable: A variable whose values are labels or groups, e.g. traffic channel, device type or plan tier.
causation (correlation is not causation): A cause-effect link; a correlation alone can also come from reverse causation, a confounder or chance, so causality needs an experiment.
central limit theorem: For large enough samples the sample mean is approximately normally distributed, even if the data are not.
centroid: The centre of a cluster: the mean of its members on every variable.
champion: A person inside the customer's company who wants the purchase to happen and actively moves it forward with colleagues. A champion is not the same as the budget owner: liking the product is not the power to pay for it.
change control: A light agreed rule for how changes to scope, date or budget get decided: who may decide which size of change, how the impact is checked and where the decision is written down. Small changes go to the lead, big ones to the sponsor; no committee is needed.
change request: A short written request to change what the project delivers, when or for how much, stating the reason and what it costs in days, money or other scope. It turns "can we also…" into a decision someone makes on purpose.
changelog: A human-readable list of what changed in each version, written for users and colleagues rather than for Git.
channel capacity: How many users a channel can bring at an acceptable cost. Costs usually rise as spend grows, so the best channel at small scale may not be the best at large scale.
channel conflict: A clash when your own sales team and a partner, or two partners, go after the same customer. It leads to price undercutting, confused buyers and partners who stop selling for you; clear rules on who owns which accounts and deal registration prevent most of it.
channel partner: An outside company that sells, delivers or recommends your product to its own clients: a referral partner paid a fee for each introduced customer, a reseller that buys and resells, or an agency that bundles your product into its service. Partners add reach you don't have at the cost of margin and less control over the customer.
charm price: A price just below a round number (499 instead of 500). The left-digit effect behind it exists in some contexts and is modest; round prices can signal quality and are easier to read.
Chebyshev distance: The largest absolute difference on any single variable.
churn: The share of paying customers who stop paying during a period, usually a month: customers lost ÷ customers at the start. It includes voluntary cancellations and failed payments that are never recovered.
classification: Assigning observations to known classes, e.g. predicting whether a user will churn.
classification threshold: The predicted probability above which an observation is labelled positive, often 0.5 but tuned to business costs.
click-through rate (CTR): Clicks divided by impressions for an ad, email or link.
clone: Downloading a full copy of a repository, with its history, to a computer. Engineers do it once; this course does everything in the browser instead.
closing report: A one-page summary of delivery and result against the criteria, what was learned and what happens next.
cluster analysis (clustering): Methods that find groups of similar observations without predefined labels, e.g. customer segments.
cluster randomization: Assigning whole groups (a shared-expense group, a city) to a variant instead of single users, when users influence each other. It needs more users for the same precision.
coaching conversation: A conversation in which the lead mostly asks rather than tells, helping a person clarify the goal, look at the current situation, find their own options and commit to a next step. It suits people who have the skills but are stuck; someone who lacks the skill needs teaching first.
code review: Reading someone else's pull request before it is merged and leaving comments and a verdict: comment, approve or request changes.
coefficient of determination (R²): The share of the outcome's variance explained by the model, from 0 to 1.
coefficient of variation: Standard deviation divided by the mean; lets you compare spread of metrics on different scales.
Cohen's d: A standardised effect size: difference in means divided by the pooled standard deviation.
cohort: A group of customers who started in the same period, for example all shops that began paying in March. Following each cohort separately shows whether newer customers stay longer or leave sooner than older ones.
cohort: A group of users who share a starting event in the same period, e.g. everyone who signed up in March.
cohort analysis (cohort table): A table with one row per acquisition cohort and one column per period since joining, showing retention or revenue. Read rows for a cohort's life, columns to compare cohorts.
cohort ROI: Return on a cohort's acquisition spend: (cumulative gross profit from the cohort − spend) ÷ spend, at a stated age such as day 90. Revenue in a calendar month mixes old and new cohorts and can't replace it.
cohort-based forecast: A forecast of active users built by adding up future cohorts: expected new users per period times their retention curve.
cold outreach: Contacting people who don't know you (calls, emails, LinkedIn messages); its main purpose is to get the first few conversations so you no longer need it.
commercial proposal: A written offer to one buyer that restates their problem and goals, the proposed scope, the price and terms, and the next steps. A strong one is built from the buyer's own numbers gathered in discovery, not from a generic price list.
commission: A fee the broker charges for placing or closing a trade; small per trade, large over many trades.
commit: One saved step in a project's history: a snapshot of the files with an author, a date, a message and a unique id (hash). GitHub shows it as the changes against the previous commit.
commit and best case: Two forecast levels: deals very likely to close (commit) and all deals that could close with luck (best case).
commit hash: The unique id of a commit, a long string of letters and digits. GitHub usually shows the first seven characters, such as `a41c09e`.
commit history: The ordered list of commits that led to the current state of a branch or a file. On GitHub it opens from the commit counter or the `History` button.
commit message: The short text an author attaches to a commit to say what changed and why. The first line is the summary shown in lists.
commitment: A sign a customer is serious because they give up something they value: time, reputation or money.
commitment currency: What a customer pays with to show interest: time, reputation risk or cash; compliments are a currency worth nothing.
company share: A unit of ownership in a company that gives a claim on part of its profits and value.
company-specific risk: The risk that one company does badly for its own reasons; holding many companies largely removes it.
competitive alternative: Whatever customers would use if your product did not exist: a rival app, but also a paper notebook, a spreadsheet, phone calls, a messenger chat or an employee who does the job by hand.
competitive alternative: Whatever a customer would do if you didn't exist: another provider, a free substitute, a do-it-yourself route or doing nothing at all. Your real market is defined by these alternatives, not by the businesses that look like you.
competitor scan: A regular, written look at the alternatives your customers consider, built only from public sources and honest conversations: websites, published prices, ads, reviews, public posts and what customers tell you. Pretexting, deception and paying insiders are never part of it.
complainer (vs customer): Someone who grumbles about a problem but has never looked for a solution; if they haven't searched for a fix, they won't look for or buy yours.
complement of an event: Everything that is not the event: P(not A) = 1 − P(A). Retention is the complement of churn: 8% monthly churn means 92% retention. "At least one" is often easiest as 1 − P(none).
compliance vs commitment: Compliance is doing what was asked because of position or pressure; commitment is doing it because the person agrees and owns it. Only commitment survives when the lead is not watching.
compliment: Praise for you or your idea ("Love it!", "Sounds great") that costs the speaker nothing and tells you nothing about real demand.
compound interest: Interest earned on earlier interest as well as on the original amount, so savings grow faster the longer they stay.
compounding: Growth in which returns are added to the balance and then earn returns themselves, so the balance grows faster over time.
concentrated portfolio: A portfolio where a few holdings, one sector or one country make up most of the money, so one bad outcome can sink the whole.
concentration risk: The danger of depending on one or a few customers for a large share of revenue: if such a customer leaves, cuts volume or presses on price, the business has little room to say no. It is tracked as the largest customers' share of revenue, with an internal limit that triggers action.
concierge MVP: A first version where the founders deliver the result by hand, with spreadsheets, calls and messages, behind a simple front end. It tests whether customers value and pay for the outcome before anything is automated.
conditional probability: The probability of A when you already know B is true, written P(A | B) and read "A given B": P(A and B) ÷ P(B). The condition shrinks the denominator to the cases where B holds.
confidence (on a roadmap): An explicit estimate of how likely an item is to be delivered within its timeframe, often shown as a percentage per column (e.g. Now 80%, Next 50%, Later 20%) or as a line separating commitments from stretch items.
confidence interval (CI): A range of plausible values for a parameter; a 95% CI is built by a method that captures the true value in 95% of repeated samples.
confidence level: The long-run share of intervals that contain the true value, typically 95%; equals 1 - alpha.
confounding variable (confounder): A third variable that affects both the supposed cause and the outcome, creating a spurious correlation.
confusion matrix: A 2x2 table of true/false positives and negatives for a classifier.
contingency reserve: Money or time set aside in the plan for risks you have already named, sized from their likely cost. The project lead can use it when such a risk happens, without asking for a new budget.
contingency table: A table of counts for combinations of two categorical variables, e.g. variant x converted / not converted.
continuous validation: Regularly re-checking, for example once a quarter, that the product still solves the customers' most important problem, that the problem is still urgent, and that the founders still care about it.
contribution margin: What a sale leaves after the costs that come with it (variable costs such as a tutor's payout, payment fees and video minutes). It is what pays for fixed costs and then becomes profit.
contribution margin ratio: Contribution margin as a share of the price: how many kopiykas of every hryvnia of sales are left to cover fixed costs.
control group: A comparable set of customers or regions that did not receive the campaign, used to estimate what would have happened anyway.
control group: The group that does not get the change and serves as the baseline.
controlled experiment: A study where the researcher assigns the treatment, so a difference between groups can be attributed to it.
conversation prep: A short team session before conversations to agree on the 3 big questions, best guesses about the customer and the commitment to ask for; answer anything researchable online first.
conversation review: Going through notes and quotes with the team after conversations to update beliefs and the 3 big questions, and to discuss which questions worked.
conversion rate: The share of users who complete a target action: conversions / users. A proportion between 0 and 1.
conversion to paid: The share of a stated group, such as paywall viewers or a sign-up cohort, who made a first payment. Always name the denominator.
conversion window: The time a user has to complete the next funnel step for it to count, measured from entering the funnel.
correlation: A statistical association between two variables: when one goes up the other tends to go up (positive) or down (negative).
correlation: How closely two investments move together, from −1 (opposite) to +1 (in step); low correlation makes diversification work better.
correlation matrix: A symmetric table of correlation coefficients for every pair of variables, with 1 on the diagonal.
cost allocation: Assigning shared costs (office, finance team, platform) to products, subjects or teams by some key. Useful for pricing and reporting, dangerous for decisions: allocated costs usually don't disappear when a product is dropped.
cost floor: The lowest price at which a sale still covers its own variable costs (payout, payment fee, per-use costs) and leaves the contribution the business needs. Built from contribution, not from fixed costs spread over a guessed volume.
cost of an early-payment discount: The yearly rate implied by a discount for paying early: d ÷ (1 − d) × 365 ÷ (days saved). 2% for paying on day 10 instead of day 60 is 2/98 × 365/50 ≈ 14.9% a year; compare it with what borrowing costs.
cost of capital (WACC): The return lenders and owners expect for financing the company, blended by their shares (weighted average cost of capital).
cost of delay: The value a business loses for each unit of time an item is not delivered, e.g. revenue missed per week before a seasonal peak. It makes urgency explicit when comparing items of similar value.
cost of revenue: The costs of delivering what was sold, such as video minutes, payment fees and, for a principal, provider payouts. Revenue minus cost of revenue is gross profit.
cost per enquiry: Channel spend divided by the enquiries (leads) it brought. Useful as an early signal, but misleading on its own: the cheapest enquiries can turn into few paying customers.
cost per paying customer: Everything a channel costs, including fees and refunds, divided by the customers who paid and stayed. Comparing channels on this, and on the contribution those customers bring later, often reverses a ranking by cost per enquiry.
cost per thousand views (CPM): What it costs to show a message a thousand times. It measures cheap attention, not whether the people who saw it could ever become customers.
cost per use: A cost the business pays each time a feature is used, such as AI inference billed in USD per request; it makes "unlimited" plans risky for the heaviest users.
cost per useful contact: Spend divided by the views or contacts that reach your target audience (here, parents or adult learners, not younger teens). Choosing media on this instead of on reach or cost per thousand views often reverses the choice.
cost to serve: What it costs to deliver and support a customer, such as coordinator time and paid no-shows, separate from the cost of the product itself.
cost-plus pricing: Setting a price by adding a fixed markup to the cost per unit. Simple, but blind to what buyers would pay and circular when fixed costs are spread over a volume that itself depends on the price; use it as a floor check.
counter-offer: An answer to a buyer's request that changes some terms and asks for something in return.
counterfactual baseline: What a metric would have been without the change, estimated from a holdout: baseline × the holdout’s growth. Incremental result = actual − expected.
coupon: The fixed interest a bond pays each year, stated as a share of its face value; a 4% coupon on 1,000 dol. pays 40 dol. a year.
covariance: The average product of the deviations of two variables from their means; its sign shows the direction of the relationship.
coverage stance: How many segments you choose to serve and how differently: one offer for everyone, a few tailored offers, or a single focus. Small teams usually do better with one focus, because their time and budget don't stretch further.
credit risk: The risk that a borrower pays interest late or does not repay the bond.
critical path: The longest chain of dependent work from start to finish; its length is the shortest time the project can take. Any delay on it moves the end date, so it is where attention and extra help pay off.
critical path (customer): The few steps in a customer's journey that a product absolutely must get right for anyone to adopt it. Solving them comes before any other improvement.
critical problem: The problem that matters most to an audience: it is painful, frequent, mandatory, eats time or money, and people already patch it with their own spreadsheets or paper systems. People pay to solve it and cancel other tools first.
critical value: The value of a test statistic beyond which H0 is rejected at the chosen alpha.
cumulative share curve: A curve showing, for each value x, the share of the list with x or less. It crosses 50% at the median and 25% and 75% at the quartiles; where two groups’ curves cross, their order flips.
currency controls: Government rules that limit buying foreign currency or moving money abroad; under martial law they decide whether and how a Ukrainian resident can invest abroad.
currency of a goal: The currency in which the bill for a goal will come. Saving in that currency removes currency risk for the goal.
currency pair: Two currencies quoted against each other; the price says how much of the second one buys one unit of the first.
currency risk: The risk that exchange-rate moves change what an investment is worth in the currency you will spend.
currency risk: The chance that a change in the exchange rate makes savings worth less in the currency you will actually spend them in.
currency risk (FX exposure): How much results change when exchange rates move, for example when costs are billed in dollars and revenue arrives in hryvnias.
custodian: The institution that holds investors' securities in safekeeping, separate from its own assets.
customer concentration: How much of the revenue depends on a few large customers. High concentration gives those customers power over the product and puts the business at risk if one of them leaves.
customer conversation: An informal, learning-focused talk with a potential or existing customer about their life, problems and behaviour, not a pitch or a scripted survey.
customer development: An approach to building a business by systematically learning from customers before and while building the product; customer conversations are one of its core tools.
customer segment: A group of customers who share the same problem, goals and buying context; if your conversations produce inconsistent problems, the segment is too broad.
customer slicing: Repeatedly splitting a broad segment by who wants the solution most and why, until you know exactly who to talk to and where to find them.
customer-funded business: A business whose growth is paid for by its customers' money rather than by investors: through pre-sales, annual prepayments, deposits or simply revenue that arrives before the costs it covers.
customer/market risk: Uncertainty about whether customers want the solution, will pay for it and exist in large enough numbers; this is what customer conversations test best.

D

daily loss limit: A fixed amount of loss for one day after which you stop trading until tomorrow.
dark pattern: An interface design that tricks or pressures people into choices they would not otherwise make: pre-ticked paid extras, hidden cancellation, confirm-shaming, countdowns that reset.
data minimisation: Collecting and keeping only the personal data you need for a stated purpose.
DAU, WAU, MAU: Daily, weekly and monthly active users: distinct users who did a qualifying action in a day, a 7-day or a 30-day window. What counts as 'active' must be defined.
day-N retention: The share of a cohort that is active exactly on day N after joining. Strict and precise, but noisy for products not used daily.
deal desk: A small team, or a written set of rules, that approves non-standard deals: discounts above a threshold, long payment terms, custom contract clauses. It keeps prices consistent across buyers and shows what each exception costs in margin before anyone says yes.
deal qualification: Checking early and honestly whether a deal is real: is there a problem worth paying to solve, who pays, by when, and what the buyer will do next. Dropping a weak deal early is a good result, not a failure.
deal registration: A partner-program rule: a partner that finds an opportunity first registers it with the vendor and, once approved, gets protection for a set period, such as a better margin or a promise that the vendor's own team won't compete for that deal. It rewards partners for finding new business and stops two sellers chasing the same buyer.
debt avalanche: Paying minimums on all debts and putting every extra hryvnia into the one with the highest rate. It costs the least interest.
debt financing: Raising money through loans or credit lines that must be repaid with interest on a schedule, whatever the results.
debt snowball: Paying minimums on all debts and putting every extra hryvnia into the smallest balance first. It costs more interest but gives quick wins that help people keep going.
decision log: A short shared record of each important decision: what was decided, who decided, the options considered, why, and when to revisit it. It stops the same question being reopened and helps new people understand how things got the way they are.
decision maker: The person who says yes to buying and controls the money. In a small business it is often the owner, while the people who feel the problem every day and use the product are employees.
decision maker: The person who controls the budget or signs off on a purchase; in B2B they are often not the person you're talking to, so ask where the money comes from.
decision mode: How a decision will be made, named in advance: the lead decides, decides after consulting, the group decides together, or the decision is delegated.
decision rights: An agreement on who decides a given question, who must be consulted, who has to agree and who can veto. Making it explicit in advance avoids fake consultation and decisions that stall because everyone assumes someone else owns them.
decision rule: What the team will do for each possible test result, written before the test starts: ship, don't ship, or iterate, and at what effect size.
decomposition of a total: Splitting a total or a change into parts that add up exactly, such as SS_total = SS_between + SS_within, or plan vs actual = volume + mix + price.
deductible: The part of a loss you pay yourself before insurance pays. A higher deductible usually means a cheaper policy.
default alive: A company is default alive if, at its current costs and revenue trend, it reaches break-even before its cash runs out without raising more money; otherwise it is default dead.
deferred revenue: Money received for lessons or service not yet delivered. It sits on the balance sheet as a liability and turns into revenue as the company delivers.
definition of done: A short checklist the team applies to every piece of work before calling it finished, such as reviewed, tested and documented. Acceptance criteria are specific to one deliverable; the definition of done is the same for all of them.
deflating: Turning a future amount into today’s money by dividing by the growth of prices: amount ÷ (1 + i)ⁿ. 184,083 UAH in two years at 8% inflation is 184,083 ÷ 1.08² = 157,821 in today’s money.
deflecting compliments: Politely ignoring praise and steering back to facts, e.g. replying to "Love it!" with "How do you handle this today?"
degrees of freedom (df): The number of values free to vary once the estimated quantities are fixed, e.g. n - 1 for one sample, n1 + n2 - 2 for a two-sample t-test.
delegation: Handing a piece of work, together with the authority it needs, to someone else while keeping responsibility for the result. Done well, it frees the lead's time and grows the person; done as dumping, it does neither.
delegation brief: A short written handover of a task: the outcome wanted and why, the limits (time, budget, quality), what the person may decide alone, when you will check in and what counts as done.
deliverable: A concrete thing a project hands over and someone can check, such as a curriculum, a diagnostic test or a landing page. Deliverables are outputs; the goal is the change they are meant to cause.
delta (Δ): The change in a quantity: ΔQ = Q_new − Q_old. A negative Δ is a decrease. ΔQ% is the same change divided by the old value.
dendrogram: A tree diagram of hierarchical clustering; cutting it at a chosen distance gives the clusters.
dependency: A link where one piece of work cannot start or finish until another one does, inside the project or outside it. Hidden dependencies, such as an expert review nobody scheduled, are a common reason projects slip.
dependent variable (outcome): The variable a model explains or predicts, e.g. revenue per user.
deploy: Putting a version of the code onto the live servers so users see it. Often happens automatically after a merge into `main`.
deposit guarantee: A state-backed scheme that repays depositors if their bank fails. In Ukraine it covers deposits and accounts of individuals and sole proprietors; the payout limit is set by law and is different during martial law and after it.
depreciation and amortization: Spreading the cost of a long-lived asset over the years it is used. A cost in the P&L that moves no cash in that period.
descriptive statistics: Numbers and charts that summarise a dataset (typical value, spread, shape) without generalising beyond it.
design effect: How many times more users a test needs when whole groups are randomized: 1 + (m − 1) × ICC, where m is the average group size and ICC how alike members of one group behave.
desirability, feasibility, viability: Three lenses for judging an idea: do customers want it, can we build it, and can the business make it pay? A simple score (e.g. 1–3 on each, summed) favors ideas that are strong on all three.
devaluation: A fall in the value of a currency against other currencies, so goods priced abroad cost more in that currency.
deviation: The difference between a value and the mean; deviations always sum to zero.
diff: A view of what changed between two versions: removed lines in red with a minus, added lines in green with a plus.
differentiation value: What the differences between our offer and the next-best alternative are worth to a particular buyer, in money: positive for what we do better, negative for what we do worse.
differentiator: A difference that counts. It passes four checks: it is relevant to the customer's choice, distinct from what the alternatives already say, provable with something the customer can see, and deliverable to every customer. A claim that misses one is decoration, not a reason to choose you.
digging: Asking follow-up questions to uncover the motivation behind a request, opinion or strong emotion: "Why do you want that?", "What would that let you do?"
diluted effect: An effect on everyone that equals the effect on those exposed times their share: +3 pp for the 15% who see a change is 3 × 0.15 = +0.45 pp overall.
dilution: The drop in the founders' ownership percentage when the company issues new shares to investors. Each funding round leaves the founders a smaller slice of the company and of any future sale.
dilution: Including users who never saw the change in the analysis. The true effect gets spread over more people and becomes harder to detect.
dimensionality reduction: Replacing many correlated variables with a few summary variables (factors or components).
discount break-even volume: How much a buyer must purchase for a discounted deal to leave the seller the same total contribution as the full-price one: required volume = old volume × contribution per unit before the discount ÷ contribution per unit after it. Because the discount comes straight out of contribution, the extra volume needed is much larger than the discount percentage.
discount break-even volume: The extra volume a discount needs to keep total contribution unchanged: ΔV = d ÷ (m − d), where m is the contribution margin ratio and d the share of price the discount takes out of margin. New volume = V × m ÷ (m − d).
discount factor: The multiplier 1 ÷ (1 + r)ᵗ that turns money received in t periods into its value today. At 25% a year: 0.8, 0.64, 0.512…
discount policy: Written rules for who may get which discount, how much, in exchange for what, and who approves exceptions, so discounts buy something and stay consistent.
discount rate: The annual rate used to convert future cash flows into today's money. It reflects what the money could earn elsewhere at similar risk.
discounted LTV: The contribution margin a customer is expected to leave over a stated horizon, with each future period converted into today's money at a discount rate.
discounted payback period: How long it takes for discounted cash flows to repay the investment. Like any payback measure, it ignores everything that happens afterwards.
discovery call: An early conversation in which the seller mostly asks and listens: what problem the company has, what it costs them, who decides and who pays, and what happens next. Its goal is to learn whether there is a real deal, not to present the product.
discriminant analysis: Finds boundaries (discriminant functions) that best separate known groups using predictors; groups minus one functions.
disqualifier: A trait that rules a company out as a customer, however eager it looks: for example no budget owner who can be reached, a need the product cannot meet, or a service cost that eats the margin. Writing disqualifiers down saves the team from deals that cost more than they bring.
distance metric: A rule for measuring dissimilarity between observations: Euclidean, Manhattan or Chebyshev.
distributing fund: A fund that pays its dividends out to investors in cash.
distribution: How often each value (or range of values) of a variable occurs.
diversification: Spreading money over many different investments so one failure does little damage to the whole.
diversification: Spreading money across many investments so that one failure can't sink the whole plan.
dividend: A share of a company's profit paid out to its shareholders.
doing nothing (status quo): The alternative of not buying at all, or putting the decision off: waiting until spring, studying alone, living with the problem. It is often the strongest competitor, because it costs nothing and needs no effort.
dollar-cost averaging: Investing a fixed amount at regular intervals, so you buy more units when prices are low and fewer when they are high.
draft pull request: A pull request marked as work in progress. It cannot be merged until the author clicks `Ready for review`.
drawdown: The fall in value from a previous peak to a later low, as a percentage of the peak.
drawdown: The fall of the account from its peak to a later low, shown as a percentage.
drip pricing: Showing a low headline price and adding unavoidable fees step by step during checkout, so the buyer sees the real total only at the end. As of October 2026, EU rules require the total price before an online purchase and Ukrainian rules require clear price information before purchase, so drip pricing risks misleading buyers under both.
driver-based forecast: A forecast built from the operational numbers that cause the financial ones (learners, lessons per learner, price, payout) instead of last year's totals plus a percentage.
DSO (days sales outstanding): The average number of days it takes customers to pay after an invoice: receivables divided by credit sales, times the days in the period.
due diligence: The detailed check a buyer runs before closing a deal to confirm that everything the seller claimed is true: finances, metrics, contracts, code, legal risks. Sellers should also check the buyer.
dunning: The process of recovering failed subscription payments: automatic retries, messages asking the customer to update their card, a grace period and, if nothing works, a pause or cancellation.
duration: A measure of how sensitive a bond's price is to interest rates: price change ≈ −duration × change in yield.
duration: The calendar time from a task's start to its finish, including waiting, reviews and days off. It depends on effort, but also on who is available, what the task waits for and how much of it can run in parallel.

E

early adopter: A customer who tries a new product while it is still rough, buys into what it could become, and gives feedback. Early adopters forgive gaps, but expect fast progress in return.
early evangelist: A first customer who has the problem, knows it, has searched for and patched together a solution, and has budget; they commit before it's rational.
earn-out: Part of a company's sale price that is paid only if the business reaches agreed goals after the sale, usually while the founder keeps working in it. The safest approach is to treat it as a possible bonus, not guaranteed money.
earned value: The budgeted value of the work actually done: each task's full budget multiplied by the share of it completed. Compared with planned value it shows whether you are behind schedule, and compared with actual cost whether the work costs more than planned.
EBITDA: Earnings before interest, taxes, depreciation and amortization: operating profit after paying everyone, owners included at a market salary, but before financing, tax and accounting write-downs. Larger companies are often valued as a multiple of it.
economic buyer: The person who controls the budget a purchase is paid from and can say the final yes or no, often a finance director or a department head. A deal without access to this person is a hope, not an opportunity.
edge: In this course: the average gain per trade after costs. A plan has an edge only if that average is above zero over enough trades.
effect size: How big a difference or relationship is, independent of sample size, e.g. absolute lift, relative lift or Cohen's d.
effective annual rate: The yearly rate a monthly rate really adds up to once interest is charged on interest: (1 + monthly rate)¹² − 1.
effective hourly rate: What a solo worker really earns per hour actually worked, after taxes and unpaid time (preparation, messages, no-shows), as opposed to the price per billed lesson.
effective rate: The total paid divided by the base it is paid on, such as tax ÷ income. With a fixed part, the effective rate is higher on a small base than the percentage in the rule.
effective tax rate: Total tax divided by income. With a percentage plus a fixed amount, it is highest when income is low: 6% of income plus 5,707.02 UAH a quarter is 15.5% on 60,000 and 9.8% on 150,000.
effort: How much work a task takes, counted in people's working hours or days, as opposed to how long it takes on the calendar (duration). Two people do not halve the calendar time when the work cannot be split or needs time to hand over.
eigenvalue: How much of the total variance a factor explains (the sum of its squared loadings).
elasticity as a ratio of changes: A ratio of two relative changes, %Δy ÷ %Δx. Price elasticity is %ΔQ ÷ %ΔP (+30% ÷ −10% = −3); operating leverage is %Δprofit ÷ %Δvolume.
emergency fund: Money set aside only for a loss of income or an unplanned essential cost, sized in months of essential costs and kept where you can reach it quickly.
enabling work: A lead's work that makes others effective: answering questions, one-to-ones, planning, removing blockers.
entry cohort: The users who entered a funnel or signed up in a date range; their later steps count within the window whatever date they fall on.
equity financing: Raising money by selling a share of the company. There is no interest to pay, but the owners' share and future profits are diluted.
error bars: Lines around a point estimate showing its SD, standard error or confidence interval; always state which one.
escalation (hand-up): Passing a case or decision to someone with more authority or expertise because the current owner cannot or should not settle it.
essential costs: Spending you can't skip for a month without harm: housing, utilities, food, transport, medicine, minimum debt payments.
estimate spread (standard deviation): How uncertain an estimate is, (pessimistic − optimistic) ÷ 6; for a chain of tasks add the variances, not the standard deviations.
Euclidean distance: The straight-line distance: square root of the sum of squared differences across variables.
Euler's number e: The constant e ≈ 2.718: what 1 grows to at 100% a year with continuous compounding, the limit of (1 + 1/n)ⁿ. eˣ and ln undo each other.
event: A record that something happened in the product: who did it, what happened and when, plus optional details (properties). Events are the raw material of product analytics.
event property: A detail attached to one event, such as the amount of an expense or how it was entered. It describes that moment, not the user.
event total: How many times an event happened in a period, counting repeats by the same person. Totals grow with heavy users; unique users don't.
exchange: A marketplace where buyers' and sellers' orders meet under shared rules and become trades.
exchange spread: The gap between the rate at which a bank sells a currency and the rate at which it buys it back; you lose it on every round trip.
exchange-traded fund: A fund whose units trade on a stock exchange during the day like shares; many ETFs are index funds.
exclusion: A cause or kind of loss a policy never pays for, such as war risks in many policies unless an option is bought. Read the exclusions before paying.
exclusions: The users and events a metric leaves out on purpose, such as staff accounts or server-created events, and how they are recognized.
exclusivity: A clause in a letter of intent that bars the seller from talking to other buyers for a set period while the buyer runs due diligence and prepares the final contract. Also called a no-shop clause.
exit: The moment founders turn their ownership into money, usually by selling the company, fully or partly, to another business or investor.
expansion: Selling more to an existing client: more users, another team or a new program.
expansion revenue: Extra revenue from existing customers: more seats or hours, new teams or departments, or a larger package. In B2B it often comes from proving results in one team and then being introduced to the next.
expectancy: The average result of one trade after costs, computed from many trades; positive means the plan earns over time.
expected frequency: The count a cell would have if the variables were unrelated: row total x column total / grand total.
expected loss: The average cost of a risk over a period: the chance it happens times the size of the loss. Comparing it with a premium shows how much of the premium pays for the insurer's costs and profit.
expected return: A reasonable central estimate of future return, always uncertain; honest communication gives it as a range with a horizon.
expected value: The probability-weighted average of the outcomes: EV = Σ p·x, with the probabilities adding up to 1. It is what you would get on average over many similar bets, not the result of any single one.
expected value of an estimate: The weighted average of a three-point estimate, (optimistic + 4 × most likely + pessimistic) ÷ 6.
expense ratio: The share of your money a fund takes every year for running it. It is charged whatever the return.
extrinsic motivation: Doing the work for something outside it: pay, a bonus, status or avoiding a penalty. It works well for simple, countable tasks and less well when the reward pulls attention away from quality or learning.

F

F-statistic (F-ratio): In ANOVA, between-group mean square divided by within-group mean square; large values mean groups differ.
F-test for equality of variances: The ratio of the larger to the smaller sample variance; tests whether two groups differ in spread.
face value: The amount a bond repays at maturity and the base its coupon is calculated on.
fact log: A running list of dated observations about someone's work, kept through the period, so evaluation rests on the whole period and not on the latest or loudest event.
factor (in ANOVA): A categorical explanatory variable whose levels define the groups, e.g. landing page version or traffic channel.
factor analysis: Explains correlations among many observed variables by a few hidden factors; used for surveys and to reduce dimensions.
factor loading: The correlation between an observed variable and a factor.
factor rotation (orthogonal, oblique): Rotating factor axes so each variable loads strongly on one factor; orthogonal keeps factors uncorrelated, oblique allows correlation.
fair-use limit: A stated cap on how much of a feature a plan includes, set so that typical users never feel it while the heaviest users cannot make the plan lose money.
fairness at work: How fair people find what they get (pay, workload, promotion), how it was decided and how they were treated along the way. People accept an outcome they dislike far more readily when the process was consistent and explained.
fake consultation: Asking for opinions when the decision is already made; it costs trust more than not asking at all.
fake door test: A cheap demand test: show a button, page or price for something that does not exist yet and count how many people try to use or buy it before deciding to build it.
fake investment platform: A site or app that imitates a broker or exchange, shows invented profits and takes deposits it never returns, often demanding a "tax" or "fee" to withdraw.
fake-door test: A page that shows a real price for an offer that doesn't exist yet. On click it says so plainly and offers a waitlist; it never takes payment. Clicks show interest at that price, not purchases.
false breakout: A breakout that reverses back into the old range, trapping those who entered late.
false discovery rate (FDR): The expected share of false positives among significant results; controlled by the Benjamini-Hochberg procedure.
false negative: Evidence that makes you drop a good idea, often caused by asking the wrong people or the wrong questions.
false positive: Evidence that makes you believe an idea works when it doesn't, e.g. polite enthusiasm mistaken for demand; more dangerous than no data because it raises confidence.
false precision: Reporting more digits than the inputs justify, such as a forecast of 1,982,437 built from three guesses. Report a rounded value or a range instead.
false urgency: A deadline or scarcity claim that isn't true, such as a "last chance" offer repeated every week. It erodes trust and can break consumer-protection rules.
false urgency: Claiming that a price or offer ends soon, or that places are almost gone, when it is not true. As of October 2026, under EU consumer law a false claim that an offer is available only for a very limited time is always unfair; false scarcity is judged case by case as a misleading practice, and the course treats both as off limits.
fan chart: A chart that shows a range of possible future paths as widening bands around a middle line.
feature: A specific capability or piece of functionality the team builds to solve a problem. On an outcome-based roadmap, features appear, if at all, under the theme they serve.
feature branch: A short-lived branch for one feature or fix, merged back when the work is done.
feature factory: A team or company that measures success by how many features it ships rather than by the outcomes they produce, and rarely checks whether shipped work changed anything.
feature flag: A switch that turns a feature on or off for some or all users without a new deploy, so unfinished or risky work can be merged and deployed while staying hidden.
feature request: A customer's suggestion of what to build; treat it as a clue to an underlying need to understand, not an item to add to the backlog.
fee drag: How much smaller a final balance ends up because of costs, which grows with every year of compounding.
fee drag: How a yearly fee on the balance compounds against the return: net rate = (1 + r)(1 − f) − 1. 5% with a 2% fee leaves 2.9% a year; over 20 years the fee takes about half of the growth.
feedback on behavior: A specific message about something a person did, its impact and what should happen next, given soon and in private when it is corrective. It describes actions, not character, and starts by asking for the person's view.
financial buyer: A buyer who acquires a company for its profits and growth and wants it to keep running much as before, often an investment firm with a portfolio of small software businesses.
financial goal: A wish turned into an amount, a date and a monthly saving number.
financial leverage: Using borrowed money to finance the business. It raises the owners' return when things go well and deepens losses when they don't, because interest must be paid either way.
finite-population correction: A factor √((N − n) ÷ (N − 1)) that shrinks the standard error when the sample is a large part of a small population. Surveying 400 of 1,120 learners multiplies the SE by about 0.80.
first sales hire: The first person a company hires to sell after the founders have been doing it themselves. It works best once there is a repeatable way to win deals to hand over (a defined ideal customer, a pipeline with clear stages, a working pitch and price), so the new person scales a process instead of inventing one.
first-party data: Data a business collects directly from its own customers with their knowledge: sign-ups, purchases, attendance, answers to its own questions. It is the safest base for segments, as long as it is collected lawfully and kept to what you need.
fishing for compliments: Asking for approval rather than information, such as "Do you think it'll work?" or "Do you like it?"; it guarantees kind but useless answers.
five-part meeting request: A five-part way to request a meeting: the problem you want to solve (without your idea), your stage and that you're not selling, where you're stuck, why this person can help, and a clear ask.
fixed cost: A cost that doesn't change with volume within a period and a range of activity, such as salaries of the in-house team or office rent. Fixed doesn't mean unavoidable: many fixed costs are chosen.
fixed-price contract: A contract that pays an agreed sum for an agreed result, so the contractor carries the risk of extra effort. It works when the scope and the acceptance criteria are clear before work starts; with a vague scope every change becomes a renegotiation.
flat fee on the original amount: A fee charged every period on the amount first borrowed, even as the debt shrinks. It looks like a low rate but costs far more: 1.5% a month on 12,000 repaid in four parts is about 28% a year, not 18%.
flexible spending: Spending you choose month by month and can change quickly, such as eating out, delivery, taxis, clothes and subscriptions. The first place to look when a plan doesn't add up.
float: How long a task can slip without moving the project's end date. Tasks on the critical path have zero float; float is shared along a chain, so using it early leaves none for later tasks.
fluff: Vague answers that sound like data but describe no real event: generic claims, future promises and hypothetical maybes.
FOP (sole proprietor): A Ukrainian sole proprietor: a person registered to do business in their own name, usually on the simplified tax system.
forecast: A model-based estimate of a future value, ideally with an uncertainty range.
fork: Your own copy of someone else's repository on GitHub, used to propose changes when you cannot create branches in the original.
formal authority: The rights that come with the position: assigning work, approving leave, taking part in pay and hiring decisions. It makes people comply, but on its own it rarely makes them commit.
formula with cases: A formula that branches on a condition, written with a curly bracket: the median is the middle value if n is odd and the mean of the two middle values if n is even.
founder-led sales: The early stage when the founders sell themselves: they run discovery calls, write proposals and close the first deals. It is how a company learns who buys, why and at what price, and that learning has to be written down before anyone else can take over.
four-question price survey: A survey that asks at what price an offer would seem too cheap to trust, a bargain, getting expensive, and too expensive, then reads an acceptable range from the answers. Also known as the Van Westendorp price sensitivity meter, after a 1976 research paper. It shows perceptions among those asked, not demand.
fraction: A number written as a/b: the numerator a divided by the denominator b. In business formulas, read the fraction line as "per" or "out of": the denominator says what the number is per.
frame of reference: The category customers file you in and therefore compare you with: "a tutor", "a language app", "a chatbot you pay for". Choosing it on purpose decides which alternatives you are judged against.
free trial: A limited time or number of uses free of charge so a buyer can try the full offer; it costs real money to serve and should be judged by the paying customers it brings, not by sign-ups.
freemium: A pricing model with a permanent free plan and paid upgrades. It works only if the free plan's limits are hit by customers who get real value, otherwise free users cost money and never convert.
frequency (absolute and relative): The count of observations with a given value (absolute) or its share of the total (relative, in %).
frequency polygon: A line chart that joins the frequencies of consecutive values; useful when there are many values.
frequency table: A table listing each value or bin and how many observations fall into it.
Friedman test: The non-parametric alternative to repeated-measures ANOVA: ranks each subject's measurements and compares rank sums.
fun money: A fixed amount in the spending plan for things you enjoy, spent without justifying it. Keeping it on purpose is what makes a plan last.
functional vs structural model: A functional model links inputs to an outcome (e.g. a regression); a structural model describes the components of the outcome.
fund domicile: The country where a fund is legally set up; it affects taxes withheld on dividends, investor protection and who can buy it.
fund factsheet: A short document listing a fund's index, costs, size, holdings, domicile and past returns.
fundamental attribution error: The tendency to explain other people's behavior by their character ("careless", "lazy") while underrating the situation they were in, such as an unclear process, a broken tool or an overloaded week. For a lead, it means checking the setup before judging the person.
funnel: A sequence of steps users should go through, with the share who reach each step. Funnel results depend on step order, the conversion window and who enters.
future promise: A statement like "I would buy that" or "I will use it"; people are consistently over-optimistic about their future behaviour.
future value: What a sum, or a series of regular contributions, grows to by a set date at an assumed rate of return.
futures: A contract to buy or sell something at a set price on a set date; traded with leverage, it can lose more than expected.
FX conversion cost: What you lose when money is changed from one currency into another, through the exchange margin and fees.

G

gap: A jump between one close and the next open with no trading in between, which can leap over a stop.
generic claim: A statement about what someone "always", "usually" or "never" does; it describes who they want to be, not what they actually did.
geometric series: A sum in which each term is the previous one times the same factor q: a + aq + aq² + … For |q| < 1 the endless sum is a ÷ (1 − q); the first n terms add up to a(1 − qⁿ) ÷ (1 − q).
Git: The version control system most software teams use. It runs on each developer's computer and records the project's history as commits.
git flow: An older, release-oriented branching model with long-lived `main` and `develop` branches plus `feature/*`, `release/*` and `hotfix/*` branches.
GitHub: A website that hosts Git repositories and adds teamwork tools on top: pull requests, reviews, issues, project boards and releases.
GitHub flow: A simple team workflow: `main` is always deployable; every change goes on a short-lived branch, through a pull request and review, and is merged and deployed soon after.
give–get trade: A negotiating rule: every concession the seller makes (a lower price, longer payment terms, extra scope) is traded for something of value in return, such as a longer contract, more volume, prepayment or a published case study. A concession given for nothing teaches the buyer to ask for more.
global stock fund: A fund that holds companies from many countries, usually weighted by market value.
GMV (gross merchandise value): The total value of everything sold through a platform, including the part that goes to sellers or tutors. A volume metric, not revenue.
goal setting: Agreeing on goals that are specific, hard but reachable, accepted by the person and followed by regular feedback on progress. Such goals reliably beat "do your best", provided the person has the skill and the goal doesn't push out what isn't measured.
goal-based budget: A marketing budget worked backwards from a goal: the paying customers you need, the conversion at each step, the contacts that requires and their cost, plus a separate slice for tests. Checked against what the business can afford and what last year's numbers say.
good-better-best tiers: A set of three plans at rising prices, each including more, so buyers with different needs and budgets choose for themselves; the middle plan is usually the one most should pick.
government bonds: Bonds issued by a national government to borrow money; in Ukraine they are known as OVDP (domestic government bonds).
government bonds (OVDP): Debt securities of the state sold for a fixed term; the yield is known in advance if you hold them to maturity, while selling earlier happens at the current market price. In Ukraine individuals buy them through banks, licensed brokers and apps.
grace period: The time during which a credit card purchase costs no interest if the whole balance is repaid by the due date.
grandfathering: Letting existing customers keep their old price or plan after a price increase, for a limited time or forever, while new customers pay the new price.
gross margin: The share of revenue left after the direct costs of delivering the product (for SaaS: hosting, third-party services used per customer, payment fees and customer support): (revenue − cost of revenue) ÷ revenue.
gross profit: Revenue minus cost of revenue: what is left to pay for the team, marketing and everything else.
gross revenue retention (GRR): Share of recurring revenue from the customers you had at the start of a period that you still have at the end, ignoring upgrades; never above 100%.
gross-up: Finding the price that leaves a target net amount after a fee taken from the price: P = net ÷ (1 − f). For 400 net after a 20% fee, P = 500, not 400 × 1.2 = 480.
growth direction: One of the ways to grow: sell more of the current offer to current customers, a new offer to current customers, the current offer to new customers, or something new to a new market. Risk rises the further you move from what you know.
growth factor: A change of r written as a multiplier, 1 + r: +50% is ×1.5, −50% is ×0.5. Chained changes multiply: ×0.5 then ×1.5 is ×0.75.
GRR (gross revenue retention): The share of last period's recurring revenue kept, ignoring expansion: (start − contraction − churned) ÷ start. It can never exceed 100%, unlike NRR.
guardrail metric: A metric that must not get worse (e.g. refunds, page speed) even if the primary metric improves.
guardrail metric: A metric the change must not worsen beyond an agreed margin, checked by its interval rather than its point estimate.

H

halo effect: A rating error in which one strong impression, good or bad, colors the judgment of everything else about a person. Rating each criterion separately against recorded facts reduces it.
hand-off note: A short written note that lets someone else take over a case or a responsibility without asking the previous owner.
handover: Passing responsibility for work to another person with what they need to carry it on: open items, contacts, decisions made and why, and where things are kept. A good handover is written, rehearsed once while the original owner is still around, and checked after.
handover to operations: The point where the project's result becomes someone's everyday job: the receiving team accepts it against the criteria, gets the documents, contacts and open issues, and the project team steps back. Until someone has accepted it, the project is not closed.
help center: A collection of short, searchable articles, usually with screenshots, that answer customers' common questions, so support sends a link instead of typing the same answer again. A good habit is to write an article the second time a question comes in.
herding: Doing what many others are doing, such as buying a popular theme, because others are doing it.
hierarchical clustering: Repeatedly merges the most similar observations or clusters until one cluster remains; the number of groups need not be known.
higher high and higher low: The pattern of an uptrend: each peak and each dip is higher than the one before. Lower highs and lower lows describe a downtrend.
hindsight: Knowing how things ended; it makes a past move look obvious and a backtest look easier than the live future was.
histogram: A chart of a quantitative variable's distribution: adjacent bars show how many values fall into each bin.
holding period: How long the money stays invested; longer periods have historically lowered the chance of ending with a loss, but never to zero.
holdout group: A small group kept without a feature or campaign for a long time to measure its cumulative effect after launch.
holdout region: A city or region deliberately left without a campaign so you can compare it with the regions that got one. The gap between them, after accounting for normal differences, estimates what the campaign added.
home bias: Holding far more of your own country's investments than its share of the world market.
hotfix: An urgent fix for a problem in the live product, shipped outside the normal release rhythm.
hurdle rate: The minimum return a project must beat to be worth doing, usually the cost of capital plus a premium for extra risk.
hybrid planning: Planning that keeps a fixed date and a few milestones from a plan-driven approach while doing the work in short iterations with a reviewed backlog. It suits projects where the deadline cannot move but the details are still being learned.
hypothesis testing: A procedure that decides whether data give enough evidence against a null hypothesis.
hypothetical question: A question about an imagined situation ("Would you…?", "Could you see yourself…?"); the answers are guesses, not evidence.

I

ideal customer profile (ICP): A description of the kind of company that gets the most value from the product and is worth the most to the seller: industry, size, situation and signals that can be checked. It is built from real won and lost deals, not from wishes.
illiquidity: How hard it is to sell an asset quickly at a fair price; an apartment or a private stake can take months to sell.
implications of a problem: What a problem actually costs the customer in money, time or risk; it separates problems people will pay to solve from annoyances they live with.
important question: A question whose answer could change or kill your business plan; if a surprising answer wouldn't change anything, the question wasn't important.
incentivized sign-ups: New users who joined because a partner or promo paid them something for signing up, such as a bank bonus. Many sign up for the reward, not the product, and retain worse than organic users.
income smoothing: Paying yourself the same amount every month from a buffer account that absorbs good and bad months.
incremental buyers: Buyers a promotion actually added, who would not have bought at the full price; everyone else in a sale got a discount they did not need.
incremental CAC: Spend divided by the customers it actually added beyond what would have come anyway. Expected = before × the holdout's growth; incremental = actual − expected; incremental CAC = spend ÷ incremental.
incremental margin: The extra contribution margin that exists only because of a marketing activity: results above the baseline, multiplied by the margin per deal or unit. It is the honest numerator for judging a campaign, unlike total revenue in the period.
incrementality: The customers, sales or contribution that exist only because of a marketing action, measured against a baseline or a holdout. Returning customers who would have come anyway are not incremental.
incrementality: The part of a result that happened only because of a campaign or channel, measured against a holdout or a geo test. Attributed conversions are often not incremental.
independent events: Events where one tells you nothing about the other. For them "A and B" multiplies: P(A and B) = P(A) × P(B). Five independent checks that each stay quiet with 0.95 all stay quiet with 0.95⁵ = 0.774.
independent samples: Groups made of different, unrelated observations, e.g. users in variant A vs users in variant B.
independent variable (predictor): A variable used to explain or predict the outcome, e.g. ad spend or number of sessions.
index: A rule-based list of securities, such as all large companies in a region, whose combined value is tracked as one number.
index fund: A fund that holds the securities of an index in the same proportions instead of picking them.
index fund: A fund that holds all the shares or bonds of a market index instead of picking winners, usually at a low fee.
index fund: A fund that holds many shares in the same proportions as an index, so one purchase spreads the money widely.
individual development plan: A short written plan, owned by the person and agreed with the lead, naming one or two skills to grow, the work that will stretch them, the support needed and how progress will be seen. Most growth comes from real assignments with feedback, not from courses alone.
inflation: The general rise in prices over time, which lowers what a fixed amount of money can buy.
inflation: The rise in the general level of prices, which means each hryvnia buys less over time.
influence: The ability to change what people do because they trust your judgment, not because you can order them. It is earned through competence, keeping promises and fair treatment, and it lasts longer than authority alone.
information criterion (AIC, BIC): A model-comparison score that rewards fit and penalises the number of parameters; lower is better.
input metric: A metric a team can move directly that feeds a higher-level metric, such as the share of new groups with a second member.
installment plan: Buying now and paying in equal parts. Often advertised as zero percent, but it can hide a monthly fee or a higher price than paying at once.
instrument: Anything you can trade: a share, a fund, a currency pair, a futures contract or a coin.
insurance record: The months and years for which social contributions were paid for a person. Reaching the required record is a condition for the state pension; the requirement changes over time, so check the current rule.
interaction effect: When the effect of one factor depends on the level of another, e.g. a discount works on mobile but not on desktop; shows as non-parallel lines.
interaction term: A term that multiplies two inputs, b·x₁·x₂. It makes the effect of one input depend on the value of the other.
intercept: b0: the predicted outcome when all predictors equal zero.
intercept of a line: The a in y = a + b·x: the value of y when x = 0. In profit = c·n − F it is −F, the fixed costs with no sales.
interest coverage: Operating profit divided by interest due: how many times the business earns its interest. Near or below 1, interest is paid from cash the business doesn't generate.
interest rate risk: The risk that bond prices fall when interest rates rise; longer bonds are hit harder.
interests vs positions: A position is what someone says they want; an interest is the reason behind it (a need, worry or goal). Two opposite positions can often be resolved once the interests underneath are on the table.
internal traffic: Activity from the team's own accounts: QA, staff, test devices. It must be excluded from quality and volume metrics, and the flag that marks it is often incomplete.
interquartile range (IQR): Q3 minus Q1: the spread of the middle 50% of the data; robust to outliers.
intrinsic motivation: Doing the work because it is interesting, meaningful or a source of growth in itself. It is supported by autonomy, a sense of competence and connection with others, and can be weakened by controlling rewards.
investing: Putting money into assets such as shares or bonds for years, accepting ups and downs in exchange for a higher expected return.
investing: Putting money into assets to hold for years, relying on growth and income rather than on short price swings.
investment policy statement: A short written plan: goal, horizon, asset mix, contributions, rebalancing rule and what you will do in a fall.
investor protection scheme: A system that compensates clients up to a limit if a regulated broker fails and their assets are missing; it does not cover market losses.
involuntary churn: Customers lost because their payment failed and was never recovered (an expired, blocked or empty card), not because they chose to cancel.
iron triangle: The trade-off between schedule, scope and resources, with quality caught in the middle: when work runs late, one of the three must give, or quality quietly pays the price.
IRR (internal rate of return): The discount rate at which a project's NPV is zero. Useful as a summary, misleading when ranking projects of different size or timing.
irregular income: Income that changes a lot from month to month, as for freelancers, tutors and sole proprietors. It is planned over a year, not a month.
issue: A GitHub item for a bug, task or idea, with a discussion, labels, assignees and a state (open, closed as completed, closed as not planned).
issue (project issue): Something that has already happened and is hurting the project now, as opposed to a risk that may still happen. An issue needs an owner and an action this week; leaving it in the risk register with a probability hides it.

J

job design: Deliberately shaping what a role contains so people can do it well and grow in it. Research links five features to motivation: variety of skills, a whole piece of work, work that matters to someone, autonomy and feedback from the work itself.
job story: A need statement in the form "When [situation], I want to [motivation], so I can [expected result]". It focuses on context and motivation rather than on a user persona.

K

k-means clustering: Splits data into k clusters by alternately assigning points to the nearest centroid and moving centroids to cluster means.
Kaiser criterion: Keep only factors with an eigenvalue of at least 1.
Kano model: A way to classify product attributes by how they affect satisfaction: basic expectations cause dissatisfaction when missing, performance attributes satisfy in proportion to how well they work, and delighters please without being expected. Over time delighters turn into expectations.
keeping it casual: Running early customer conversations as quick, relaxed chats rather than scheduled formal interviews; people speak more honestly and you learn faster.
key account: One of the few customers whose revenue, influence or growth potential is large enough to get a named owner and a written plan: their goals, the people on both sides, risks, growth opportunities and next steps, reviewed on a fixed rhythm. The plan's aim is a relationship that survives any one person leaving on either side.
key information document: A short standard document an EU fund must give retail investors, with its costs, risk score and scenarios; funds without one are usually not sold to EU retail investors.
key result: A measurable indicator with a baseline and a target that shows progress towards an objective, e.g. "raise the 60-day subscription renewal rate from 42% to 50%". A good key result describes an outcome, not a task.
key-person risk: The danger that the business stalls when one person, often the founder, is sick, on holiday or gone, because only they know how things work. Documentation, automation and hiring reduce it.
Kruskal-Wallis H test: The non-parametric alternative to one-way ANOVA, based on rank sums of three or more groups.

L

label: A coloured tag on issues and pull requests, such as `bug` or `checkout`, used to sort and filter work.
lag: The delay of an average or an indicator behind the price, because it is built from past prices.
latent factor: An unobserved trait inferred from correlated indicators, e.g. 'price sensitivity' behind several survey answers.
launch stance: The combination of price level and promotion effort chosen for a new offer: for example a modest price with a strong push to grow fast, or a higher price with a quiet launch to a few customers. Pricing itself belongs to the Pricing course.
lawful basis: The legal ground on which personal data may be collected and used, such as consent or a legitimate interest that has been weighed against the person's rights. Under the EU data protection rules and Ukrainian personal data law, outreach needs one, collects only what it needs and lets people object or unsubscribe.
leading and lagging metrics: A leading metric moves early and can be acted on (trial lessons booked, enquiries from the target segment); a lagging metric shows the result later (paying families, contribution). A plan needs both, each with one owner.
leading question: A question that signals the answer you want ("Don't you hate it when…?"); it manufactures agreement instead of revealing the truth.
learning bottleneck: When customer insight lives in one person's head instead of being shared with the team, so "the customer said so" becomes an unchallengeable order.
learning goal: A goal about gaining a skill, not hitting a number; it works better than a hard result target when a person is new to a task.
least squares method: Fits a regression line by choosing coefficients that minimise the sum of squared residuals.
left-digit effect: Buyers read 649 as "six hundred and something" because they weigh the left digit most. The effect is modest and depends on context; it is never a reason to hide the real price.
legacy plan: An old plan or price that new customers can no longer choose. Keeping existing subscribers on it is called grandfathering; the fair version is time-limited, with clear notice before they move to the current price.
letter of intent (LOI): A mostly non-binding document in which a buyer sets out the main terms of a planned acquisition, such as price, payment structure and timeline, before full due diligence. It is the point to involve a lawyer.
letter of intent (LOI): A non-binding written statement that a customer intends to buy under certain conditions; weaker than payment but far stronger than words.
levels of delegation: A scale of how much freedom a person gets on a task, from "gather facts and I decide" through "propose and I approve" to "decide and tell me afterwards". The right level depends on the person's experience with this task and on the cost of a mistake.
leverage: Trading a position larger than your own money by borrowing the rest, which multiplies gains and losses on the account alike.
licensed broker: A firm allowed by the securities regulator to buy and sell securities for clients. In Ukraine its licence can be checked in the regulator's public register before sending money.
life-cycle stage: Where an offer stands now: new, growing, mature or declining. Use it to ask what the offer needs next, not as a schedule it must follow. Read the stage from the right comparison (the same months a year earlier, twelve months against twelve), not from one bad season; a brand-new offer has too little history to read this way.
lifetime deal: A one-time payment for permanent access to a subscription product, often sold through deal websites. It brings quick cash but turns future recurring revenue into a single payment, while the cost of serving the customer continues.
lift (absolute and relative): The change of a metric in the variant vs control: absolute lift in percentage points, relative lift in % of control.
Likert scale: A survey rating scale such as 1 = strongly disagree to 5 = strongly agree; an ordinal variable.
limit order: An order to trade only at your price or better, so the price is certain but the fill is not.
linear function: A relation of the form y = a + b·x: the intercept a is the value at x = 0 and the slope b is the change in y for each unit of x. Profit = c·n − F, a trend line and a tax with a fixed part are all linear functions.
linear interpolation: Estimating a value between two known points by assuming a straight line between them, such as payback = 2 + 300,000 ÷ 800,000 = 2.375 years.
linear regression: A model that predicts an outcome as a straight-line function of a predictor: y = b0 + b1 x.
liquidity: How quickly and cheaply you can turn savings into cash you can spend, without losing interest or value.
liquidity: How easily you can buy or sell without moving the price; a liquid market has many orders and a small spread.
list of 3 (big questions): The three most important things you want to learn from a given type of person, chosen with your team before the conversation and updated as you learn.
list price: The published price before any discount, promo code or fee; the starting point of the price waterfall.
listening round: A first round of short one-to-one conversations in which a new lead asks open questions and listens, before changing anything.
log-odds (logit): The natural logarithm of the odds; positive when p > 0.5, negative when p < 0.5.
logistic regression: A model for a yes/no outcome that predicts the log-odds as a linear function of predictors and returns a probability.
long position: A trade that profits when the price rises: you buy first and sell later.
losing streak: Several losing trades in a row; even a sound plan has them, and how long they get depends on the win rate.
loss aversion: The tendency to feel a loss much more strongly than a gain of the same size.
loss aversion: The tendency to feel a loss more strongly than an equal gain, which makes people hold losers and cut winners.
LTV (customer lifetime value): The total revenue (or profit) a business expects from one customer over the whole time they pay. A rough estimate: average monthly revenue per customer ÷ monthly churn.
LTV curve: Cumulative revenue (or gross profit) per user of a cohort by day or month since joining. Its shape shows when a cohort pays back and whether it's still growing.
LTV:CAC ratio: Customer lifetime value divided by customer acquisition cost: how many times a typical customer pays back what it cost to win them. A common rule of thumb for healthy subscription businesses is about 3 or more.
lump sum: Investing an available amount all at once instead of in parts over time.

M

main branch: The branch that holds the accepted, current state of the project, usually called `main` (older projects: `master`). In GitHub flow it is what gets deployed.
main effect: The average effect of one factor across all levels of the other factors.
management reserve: Money or time held outside the project's plan for surprises nobody could name in advance. The sponsor, not the project lead, decides when to release it.
Manhattan distance: The sum of absolute differences across variables, like walking along a street grid; less sensitive to outliers.
Manhattan distance: The distance measured along a grid: the sum of absolute differences Σ|xᵢ − yᵢ|. Between (6, 30) and (9, 34) it is 3 + 4 = 7, while the Euclidean distance is 5.
Mann-Whitney U test: A non-parametric test comparing two independent groups by pooling, ranking and comparing rank sums.
margin of error: Half the width of a confidence interval, e.g. about 1.96 x SE for 95%.
margin of safety: How far sales can fall before the business reaches break-even, as units or as a share of current sales.
marginal CAC: Extra spend divided by the extra users it brought. It rises as a channel scales, while the average CAC hides the rise.
marginal rate: The rate that applies to the next unit of the base, the rate of the slice you are currently in. Under rising tiered rates it is higher than the effective rate.
marginal vs average: A marginal quantity is the change between two neighbouring points, Δy ÷ Δx, such as the cost of the next customer; an average is the total divided by the total. They are equal only on a line through zero.
market line: On a value map, a line through the prices the market usually asks at each level of benefit (in the course, about 100 UAH per benefit point). An offer far above it must win on something the map leaves out; one far below it gives buyers extra value, by choice or by accident.
market maker: A firm that always quotes both a buy and a sell price, earning the spread and keeping the market liquid.
market order: An order to trade right now at the best price available, so the fill is certain but the price is not.
market risk: The risk that the whole market falls; diversification within that market cannot remove it.
market segment: A group of customers who share a need or situation and respond to an offer in a similar way, large enough to serve on purpose and different enough from other groups to need its own choices.
market timing: Moving in and out of the market based on forecasts of where it will go next.
market-cap weighting: Holding each company in proportion to its total market value, so the biggest companies get the biggest weights.
marketing strategy: The few choices that steer all marketing work: whom to serve, what to offer them, why they should choose you, and how they find you and keep buying. Campaigns, posts and ads are tactics that carry these choices out.
marketing–sales SLA: A written agreement between marketing and sales on shared definitions and promises: what counts as a qualified lead, how many of them marketing will deliver, how fast sales will follow up and what feedback goes back. It replaces arguments about lead quality with numbers both teams have agreed to.
mathematical model: A simplified formal description of a system that lets you explore scenarios without real experiments.
matrix structure: A setup in which a person answers to two lines at once, for example a functional manager and a project or partner team. It needs clear decision rights between the two, or the person is left to resolve conflicting requests alone.
maturity: The date when a bond ends and the issuer pays back its face value; shorter maturities move less when rates change.
maturity (of a bond): The date when the issuer repays a bond's face value with the last interest. Held to maturity, the result is known in advance; sold earlier, the bond fetches the market price.
mean (arithmetic mean): The sum of all values divided by their count; sensitive to outliers.
measure of central tendency: A single number describing the typical value of a variable: the mean, median or mode.
measure of variability (spread): A number describing how much values differ from each other: range, IQR, variance or standard deviation.
median: The middle value when results are sorted: half are above it and half below. With skewed returns it is often far below the average.
median: The middle value of the sorted data (the average of the two middle values when n is even); robust to outliers.
mediation: A conversation in which a neutral third person helps two sides of a conflict understand each other's interests and agree on a next step themselves. For a lead, it means hearing each person first, then bringing them together around the shared problem instead of handing down a verdict.
meeting audit: Counting a recurring meeting's minutes, people, decisions and action items to see what it really produces.
meetings anti-pattern: The habit of turning every chance to talk to a customer into a scheduled meeting; it wastes time, raises expectations and kills spontaneous learning.
merge: Combining the commits of one branch into another, for example a finished feature branch into `main`.
merge commit: A commit with two parents that joins two branches. GitHub creates one when a pull request is merged with `Create a merge commit`.
merge conflict: A situation where two branches changed the same lines differently, so Git cannot combine them automatically and a person has to choose the result.
message hierarchy: The order of what you say: one main message from the position, two or three supporting messages for different buyer roles, and the proofs under each. It keeps every channel saying the same thing in its own words.
metric: A quantitative measure tracked for a product or campaign, such as conversion rate, AOV, retention or CTR.
metric definition: The exact rule for computing a metric: which events count, which users are excluded, the time window and the time zone. Two people with the same definition get the same number.
metric gaming: What happens when one number is tied to rewards: people improve the number in ways that hurt the goal behind it, such as closing tickets fast but unresolved. Pairing the target metric with a quality check reduces it.
metric tree: A breakdown of a top metric into the input metrics that drive it, so each team can see which lever it moves.
microloan: A small, short loan, usually online, with a very high real annual cost. Rolling it over is how small debts turn into large ones.
mid price: The price halfway between the bid and the ask; a handy reference, but not a price you can actually trade at.
middle-option effect: The tendency to pick the middle of three options because it feels like a safe compromise. Honest use: a real, useful middle plan, not a fake top option added only to push it.
milestone: A group of issues and pull requests with an optional due date, used to track progress towards a release or goal.
milestone: A dated yes-or-no checkpoint where someone decides to go on, change course or stop; it takes no time itself. It is most useful when it is tied to a decision and a named decider, not just to an event being done.
military levy: A separate Ukrainian levy on most personal income, and on sole proprietors' income, paid on top of income tax or the single tax. Its rates changed in late 2024 and early 2025, and how long it will apply is not settled yet, so lessons always give the date.
minimum detectable effect (MDE): The smallest effect a test is designed to detect with the planned power; smaller MDE needs a larger sample.
minimum detectable effect (MDE): The smallest change a test is sized to detect with the chosen significance level and power. Pick it from what would matter to the product, not from what is easy to detect.
minimum payment: The smallest amount a card requires each month. Paying only this keeps most of the debt, and its interest, alive for years.
mission statement: A statement of what the organization does now, and for whom, that moves it towards its vision. A good mission creates value for others, inspires, is plausible and is specific to the business.
mix effect: The part of a change caused by a shift in the shares of items with different rates, such as more low-margin lessons in the total. Computed as actual volumes at plan rates minus actual total volume at the plan average.
mix shift: A change in an average or ratio caused by a change in who is in the group, not by a change in behavior. Example: expenses per active user fall because a wave of new users arrived.
mix-adjusted rate: A rate for one period recomputed with another period's segment mix, so that a comparison shows changes in behavior rather than changes in who arrived.
mode: The most frequent value in the data; the only measure of central tendency that works for categories.
model portfolio: A ready-made mix of funds for one risk level that many investors can follow.
momentum: How fast and how strongly price has been moving recently; a momentum gauge turns it into a number.
money date: A short, regular meeting of partners to look at the month's money together: numbers on the table, no blame, decisions written down.
money map: A one-page list of a household's accounts, cards, debts, policies, savings, regular bills, documents and contacts, so others can find and reach the money if you can't act. It never holds PINs, passwords or codes.
money milestone: A point where a young product's recurring income covers one more real bill: the first payment, the tools, one founder's living costs, both founders, proper salaries. Progress is measured by these sums, not by months or effort, and each one changes what the founders should work on.
money plan: A one-page summary of goals, the monthly plan, the cushion, debts, savings and investments, reviewed once a year.
money you can afford to lose: Money whose loss would not change your life, your bills or your sleep; only this money belongs in trading.
money-back guarantee: A promise to refund a buyer who is not satisfied, within stated terms; it lowers the risk of buying and must be honored as easily as it is advertised.
money-weighted return: An investor's own return, which counts how much money was invested at each moment.
monthly control loop: A short monthly check of the plan: compare results with the targets, find the cause of any gap, then make one of four moves: keep going, fix how the work is done, move budget to what pays, or re-forecast when the target itself was unrealistic. Scale and stop rules are agreed in advance.
MoSCoW method: A way to communicate release scope by sorting requirements into Must have, Should have, Could have and Won't have (this time). It labels priorities that have already been decided; it does not decide them.
motivation diagnosis: Finding out why someone isn't doing what is expected before acting: they can't (skill, tools, time), they won't (the work or its conditions put them off) or they don't believe the effort pays off. Each cause needs a different fix.
moving average: The average of the last N closes, recalculated each period; it smooths noise and lags the price.
MRR (monthly recurring revenue): The subscription revenue a business can expect every month from its current customers. Annual plans count as their price divided by 12; one-off payments are left out.
multi-sided market: A business serving several distinct customer groups at once (e.g. hosts and guests, users and advertisers); each side needs its own conversations.
multicollinearity: Strong correlation between predictors that makes regression coefficients unstable and hard to interpret.
multiple: How many times one quantity is another, written as 3× ("three times"). In valuation, the number a yearly figure is multiplied by: value ≈ ARR × m. A multiple means nothing without its base.
multiple comparisons problem: Running many tests (metrics, segments, variants) raises the chance that at least one is a false positive.
multiple regression: Regression with several predictors; each coefficient is the effect of its predictor holding the others constant.
must, should, could: A way to sort scope into what the project cannot launch without, what it should include if time allows and what it could add. When time runs short, you cut from the bottom instead of moving the date.
mutual action plan: A short document agreed with the buyer that lists the steps both sides must take before signing (pilot, security review, legal check, budget approval), each with an owner and a date. It turns "we'll get back to you" into a schedule both sides can check.
MVP (minimum viable product): The smallest product that solves the core problem well enough that early customers will pay for it. For a subscription app that usually means: sign up, get the main job done, and pay; everything else waits.

N

natural logarithm (ln): The power to which e ≈ 2.718 must be raised to give a number: ln(eˣ) = x. It turns powers into products, ln(aᵗ) = t·ln a, so it solves for time: aᵗ = b gives t = ln b ÷ ln a.
natural usage rhythm: How often a satisfied user needs the product: daily for messaging, weekly or monthly for splitting bills. Metrics and retention should be read at this rhythm.
needs-based segmentation: Grouping customers by what they are trying to get done and the situation they are in (an exam in May, a move abroad, a career change), then using descriptive facts such as age or location only to find them.
negative churn: When extra revenue from customers who stay (upgrades, more locations, add-ons) is larger than the revenue lost to cancellations and downgrades, so MRR grows even without new customers.
net channel contribution: Contribution from the customers a channel brought and kept, minus the channel's spend and every fee and refund, over a stated window such as 90 days.
Net Promoter Score (NPS): Share of promoters (9-10) minus share of detractors (0-6) on a 0-10 'would you recommend' question; ranges from -100 to 100.
net revenue (agent vs principal): Revenue reported as the company's own share when it acts as an agent that connects buyers and providers; a principal that controls the service reports the full price and the provider's share as a cost.
net revenue retention (NRR): Recurring revenue from the customers you had at the start of a period, including their upgrades, as a share of what they paid at the start; can exceed 100%.
net worth: Everything you own minus everything you owe; tracked once a year, it shows whether the plan is working.
netting gains and losses: Offsetting investment losses against gains within the same tax year, so tax is paid only on the net profit where the law allows it.
network effect: When the product's value for one user depends on others using it. In tests it means one user's variant can leak into another's experience.
Newcombe interval: A confidence interval for the difference of two shares built from their two Wilson intervals, combining the one-sided widths in quadrature: √(w_A² + w_B²).
next steps: The concrete, agreed actions that follow a meeting (who does what, by when); if you don't know what happens next, the meeting was pointless.
next-best alternative: What the buyer would actually do if our offer did not exist: another school, a private tutor, free videos, or nothing at all. Its price is the reference point for ours.
niche: A narrow, clearly defined group of customers who share a job, problems and vocabulary and talk to each other, for example independent car repair shops. Small enough to reach and understand, big enough to support the business.
niche: A narrow segment with specific needs that a small business can serve unusually well. A niche still has alternatives and risks; it is chosen for fit, not because it looks empty.
nominal rate: The rate a bank or bond states, before inflation and usually before tax.
nominal return: The return measured in money, before taking inflation into account.
non-parametric test: A test that makes no normality assumption, usually by working with ranks; robust to outliers and skew.
normal distribution: The symmetric bell-shaped distribution; about 68% of values lie within 1 SD of the mean and about 95% within 2 SD.
north star metric: The one metric that best captures the value users get from the product and predicts long-term success. Teams use it to align decisions, not as the only number they watch.
note-taking symbols: Short marks added to notes to tag signals such as emotion, pain, goal, obstacle, workaround, context, feature request, money, a named person and a follow-up, so notes can be sorted later.
novelty effect: A temporary change in behaviour because something is new; it fades, so short tests can overstate the effect.
Now-Next-Later roadmap: A roadmap format with three columns instead of dates: what the team is working on now, what comes next and what is planned for later, with certainty and detail decreasing from left to right.
NPV (net present value): The sum of all of a project's cash flows, each converted to today's money, minus the investment. A positive NPV means the bet earns more than the discount rate.
NRR (net revenue retention): The share of recurring revenue from existing customers that is still there after a period, counting expansion and subtracting downgrades and churn: (starting MRR + expansion − contraction − churned MRR) ÷ starting MRR. Above 100% means existing customers grow revenue on their own.
null hypothesis (H0): The default claim of no difference or no effect, e.g. 'the new checkout does not change conversion'.
number of pairs: How many ways to pick two items out of k: C(k, 2) = k(k − 1) ÷ 2. Four test variants give 6 pairwise comparisons, five give 10, ten give 45.

O

observation: One measured unit in a dataset (one user, order or session); usually one row of a table.
observational comparison: Comparing groups the team didn't assign at random, such as before vs after a release. It can show a difference but can't prove the change caused it.
obstacle: Something that stops a customer from solving a problem they want to solve (budget rules, IT policy, approvals); your product will likely have to deal with it too.
odds: The probability of an event divided by the probability it does not happen: p ÷ (1 − p). p = 0.2 gives odds of 0.25 (one to four); p = 0.5 gives 1. Back: p = odds ÷ (1 + odds).
odds: Probability of an event divided by the probability of it not happening: p / (1 - p).
odds ratio: How many times the odds change per unit of a predictor; exp of a logistic regression coefficient.
offer layers: Seeing an offer as the core result the customer wants, the product that delivers it (a lesson), and the services around it (progress notes, scheduling, support). The layers around the core are often where a real difference lives.
OKR (objectives and key results): A goal-setting method that pairs a qualitative objective with a few quantitative key results showing whether it has been reached, usually over a quarter.
one-page marketing plan: A single page with one row per marketing choice: situation, segments, first target, position, channels, messages and budget, offer and growth, metrics and review. Short enough that the whole team (or one founder) can run it and check it every month.
one-tailed vs two-tailed test: A two-tailed test detects a difference in either direction; a one-tailed test only in a direction fixed in advance.
one-to-one: A regular private meeting between a lead and one report, where the report owns the agenda. It is for the person's concerns, growth and feedback in both directions, not for a task status update.
ongoing charge: The yearly fee a fund takes from its assets, as a percentage, also called the expense ratio or TER.
open, high, low, close: The four prices that describe one candle: where the period started, its top, its bottom and where it ended.
operating cash flow: Cash generated or used by the core business in a period: profit adjusted for non-cash items and for changes in working capital.
operating expenses (opex): The costs of running the company that aren't part of delivering a specific sale: salaries, marketing, office, tools.
operating leverage: How strongly operating profit reacts to a change in sales: contribution margin divided by operating profit. The more fixed costs, the stronger the swing in both directions.
operating profit (EBIT): Gross profit minus operating expenses, before interest and taxes: what the business itself earns.
operational work: Work that repeats with no planned end, such as running lessons, paying tutors or answering support. A project usually hands its result over to it.
opinion question: A question asking what someone thinks of your idea or a price ("Is it a good idea?", "How much would you pay?"); only the market can answer it.
opportunity (deal): A potential purchase that has passed qualification: a real need, a reachable budget owner, a rough size and a timeline. A lead is just a contact or a company that showed interest; it becomes an opportunity only after that check.
opportunity cost: The value of the best option you give up by choosing another, such as the contribution of the lessons a tutor could have taught instead.
opportunity solution tree: A visual map that starts from one desired outcome, branches into customer opportunities (needs, pains, desires), then into possible solutions and the experiments that test them.
order: An instruction to the broker to buy or sell, with a type, a size and sometimes a price.
order book: The list of waiting buy and sell orders at each price; a big market order eats through it level by level.
order of magnitude: Which power of ten a number lives in: thousands (10³), millions (10⁶), billions (10⁹). Two numbers a factor of ten apart differ by one order of magnitude.
order of operations: The rule for which part of a formula to compute first: brackets, then powers and roots, then multiplication and division, then addition and subtraction; left to right within one level. Spreadsheets follow the same rule.
ordinal variable: A categorical variable whose values have a natural order but uneven gaps, e.g. a 1-5 satisfaction rating.
Osborne effect: A drop in current sales caused by announcing a future product too early, because buyers wait for the new version. It is one reason to be careful about what an external roadmap reveals.
outbound prospecting: Reaching out first to companies and people who have not contacted you, by email, phone, professional networks or events. Done well it is targeted, short, relevant and lawful, with an easy way to opt out.
outcome: A measurable change in customer behavior or business results that a piece of work is meant to cause, such as fewer abandoned carts or more subscription renewals.
outcome vs output: The distinction between what a team produces (output: features, releases, documents) and the difference those things make for customers and the business (outcome: changed behavior, solved problems, moved metrics).
outcome-based roadmap: A roadmap organized around the changes the team wants to achieve for customers and the business (themes tied to objectives and key results) rather than around a list of features with dates.
outlier: An observation far from the rest of the data (a common rule: beyond 1.5 IQR from the quartiles); can distort the mean and SD.
output: Anything a team ships or produces: a feature, a release, a campaign, a document. Output is necessary, but on its own it says nothing about whether anything improved.
outside view: Estimating from how similar past projects actually went instead of from the details of this one (the inside view).
over-sharing trap: When you visibly expose your hopes or ego ("I quit my job for this, be honest"), people protect your feelings instead of telling you the truth.
overbought: A high reading of a momentum gauge after a strong rise; it is not a signal to sell, because in a strong trend it can stay high for weeks.
overfitting: A model that fits noise in its sample and predicts poorly on new data; checked with holdout data, limited with AIC/BIC.
overfitting: Tuning a rule until it fits past data perfectly, which makes it look great there and fail on new prices.
oversold: A low reading of a momentum gauge after a strong fall; like overbought, it describes what happened and does not forecast a turn.
overtime: Hours worked beyond the agreed schedule, including messages answered outside the shift; a leading sign of overload when it concentrates on one person.
owned channel: A channel you control: your website, email list, messenger chat with consent, your own community. Slow to build, but you keep the relationship and the data.
owner earnings: A small business's yearly profit before paying its owners anything: revenue minus all costs except the founders' own pay and perks. Also called seller's discretionary earnings (SDE); buyers of small businesses often price them as a multiple of it.

P

p-value: The probability of getting a result at least as extreme as the observed one if H0 were true. It is not the probability that H0 is true.
P&L (income statement): The report of revenue, costs and profit for a period, built on the accrual principle: it shows what was earned, not what arrived in the bank.
padding: Adding hidden extra time to each task's estimate. Because work tends to fill the time given and late tasks pass their delay on, padded tasks still finish late while the project date becomes absurd.
paid-post disclosure: Clearly marking a creator's post or a review as paid or sponsored when there is a payment, a gift or another relationship behind it. Hiding it misleads customers and can count as hidden advertising under consumer-protection and advertising law.
painkiller vs vitamin: A test of urgency: a painkiller solves a problem people need fixed now; a vitamin is a nice-to-have they'll postpone.
paired (related) samples: Measurements that come in matched pairs, typically the same users before and after a change.
paired t-test: Tests whether the mean of before-after differences is zero: t = mean difference / (SD of differences / sqrt(n)).
parameter: A true (usually unknown) property of the population, such as the population mean.
parametric test: A test that assumes a distribution (usually normal) and works with means and variances, e.g. the t-test or ANOVA.
partner agreement: The contract that sets how a partner works with you: its role, commission or margin, tiers and targets, who owns the customer relationship, deal registration, use of the brand, data protection and how either side can leave. Competition law limits what it may contain: a recommended price is allowed, while fixing the partner's resale price or banning passive sales is not; specific wording is a question for a lawyer.
partner channel: Customers reached through another business or person who already has their trust, such as a school, a community or a creator. Partners recommend on their own terms; you may suggest a resale price or set a maximum, but not fix it or set a minimum.
partner marketing fund: A budget the vendor gives a partner for joint promotion, paid against agreed activities.
partner scorecard: A table that compares candidate partners on a few criteria chosen in advance (fit with your ideal customers, reach, delivery quality, overlap with your own sales, financial health), each with a weight and a score. It makes the choice explicit and comparable instead of going to whoever asked first.
passive investing: Holding a whole market through an index fund instead of trying to beat it.
passive sales: Sales that come to a partner unsolicited, for example a customer outside its territory who finds it online and asks to buy. A supplier may limit a partner's active selling into territories reserved for others, but under EU and Ukrainian competition law a ban on passive sales is a serious restriction that does not belong in partner terms.
past specifics: Concrete facts about something that already happened ("Tell me about the last time…"); the most reliable kind of answer in a customer conversation.
path to purchase: The steps a customer takes from noticing a need to buying and buying again, and what they need at each step. A considered choice (an exam tutor) has more steps and more people than a habit (a monthly club).
pay cycle: The time from one payday to the next. Tracking and planning by pay cycle, not by calendar month, shows whether the money lasts.
pay yourself first: Moving a set amount to savings automatically on payday, before any spending, instead of saving what is left at the end of the month.
payback period: How long until a cohort's cumulative gross profit per user covers its acquisition cost.
payoff: The average size of a winning trade compared with the average losing one.
paywall: The screen that asks a user to pay or start a trial to use a feature. Its conversion depends on what triggered it as much as on its design.
Pearson correlation coefficient (r): Measures the strength of a linear relationship from -1 to +1; sensitive to outliers.
Pearson's chi-square test: Tests association between categorical variables by summing (observed - expected)^2 / expected over all cells.
peeking (optional stopping): Checking results repeatedly and stopping as soon as p < 0.05; inflates the false-positive rate far above alpha.
penetration pricing: Entering a market at a deliberately low price to win volume fast, which pays only if volume, learning or network effects bring costs down or the price can later rise.
perceived vs real problem: The difference between what a customer says is wrong ("we need better messaging") and the underlying need that asking "why?" reveals ("we need everyone on the latest file").
percent (%): Hundredths: 2.5% = 2.5 ÷ 100 = 0.025. A percent is always a percent of something, its base.
percentage point (pp): The unit of an absolute difference between two percentages: 4% to 5% is +1 pp but +25% relative.
percentile: The value below which a given share of outcomes fall; the 10th percentile of simulated paths is a bad but not the worst case.
percentile: The value below which a given percentage of observations falls, e.g. the 90th percentile of page load time.
performance chasing: Moving money into whatever did best recently, often just before it cools down.
performance evaluation: A periodic, structured judgment of how a person has done against expectations agreed in advance, based on facts collected over the whole period. It should hold no surprises: anything important was already discussed in one-to-ones when it happened.
personal income tax (PIT): The main Ukrainian tax on individuals' income, such as salary and bank deposit interest; usually the employer or the bank withholds it. Some income, such as interest on government bonds, is exempt.
personalized price: A price set for an individual by automated decision-making from their data; as of October 2026, sellers to EU consumers must tell them when a price was personalized this way.
PERT estimate: A weighted mean of three guesses with weights 1, 4 and 1: E = (O + 4M + P) ÷ 6. For 4, 6 and 14 weeks, E = 7 weeks: a long pessimistic tail pulls the estimate above the most likely value.
phishing: A fake message or website that copies a bank, a shop or a state service to make people enter card details, codes or passwords.
pie chart: A circle split into sectors proportional to shares of the whole; readable only with a few categories.
pilot (proof of concept): A small, time-limited trial of the product with one team or site, with success criteria agreed in advance and a decision date. A pilot without criteria and a date tends to drift on unpaid and prove nothing.
pipeline coverage: The value of open, qualified deals for a period divided by the sales target for that period. Whether a given coverage is enough depends on the team's own win rate: it is a check, not a target in itself.
pitching: Slipping into selling or defending your idea during a learning conversation; the moment you pitch, they stop talking about their problems.
placebo: A dummy treatment that looks real; separates the effect of the change from the effect of expecting a change.
planned value: The budget of the work that should be finished by a given date, used to compare with earned value and actual cost.
planning fallacy: The habit of underestimating how long your own work will take, even when similar work has run late before. Asking how long such projects really took is the usual correction.
platform fee: What a broker or app charges for holding and trading investments, as a yearly percentage or fixed fees.
play bucket: A small share of a portfolio, capped at a level you set yourself (say 3–10%), for themes or single bets, so the urge to bet does not touch the core plan.
polynomial (non-linear) regression: Regression that includes squared or higher-power terms to fit curved relationships, e.g. diminishing returns on ad spend.
Ponzi scheme: A fraud that pays earlier investors with money from new ones and promises high, steady, "guaranteed" returns until it collapses.
pooled conversion: Conversion calculated on all deals together, as opposed to an average of rates that weights every group equally.
pooled rate: All successes divided by all trials across groups: (40 + 30) ÷ (1,000 + 200) = 5.83%. It is a weighted mean of the group rates, unlike the plain mean of rates.
pooled vs averaged rate: A pooled rate divides total events by total cases across people; an average of rates weights every person equally. They differ when people handle different volumes.
population: The whole group we want conclusions about, e.g. all current and future visitors of the shop.
portfolio drift: How a portfolio’s mix moves away from its target as some assets grow faster than others; left alone, a 60/40 mix slowly becomes mostly stocks.
position: What you currently hold in an instrument, with its size and direction.
position size: How many units you buy, set so that the distance to the stop times the size equals your chosen risk.
positioning: How a product is placed in customers' minds: compared with which alternatives, for whom, and why it is better for them. Good positioning names the category and the difference in the customer's own words.
positioning: The place you want your offer to hold in the customer's mind compared with their alternatives: what it is, who it is for and why it is the better choice for them. You position by changing the offer or how it is understood, not just the slogan.
positioning statement: An internal sentence that fixes the position: for whom, in which frame of reference, the one difference that counts and the proof behind it. It guides every message but is not itself an ad.
positive risk: An uncertain event that would help the project, managed with responses such as exploit, share or enhance.
post hoc test: A pairwise comparison run after a significant ANOVA with control of multiple comparisons (Tukey, Bonferroni, Games-Howell).
practical significance: Whether an effect is large enough to matter for the business, judged by effect size and cost, not by p-value.
practice account: An account with pretend money and real-looking prices, used to learn the routine without risking savings.
pre-money and post-money valuation: The value an investor puts on a company before its new money comes in (pre-money) and right after (post-money = pre-money + the new investment). The investor's share is the investment divided by the post-money valuation.
pre-mortem: A short exercise before a decision or launch: the team imagines it's some months later and the plan has failed, then each person writes down why. It brings out risks people would otherwise keep to themselves and turns them into checks or changes to the plan.
pre-order: Paying for a product before it exists (as on Kickstarter); the clearest proof that "I would buy it" is true.
pre-release: A test version published before the final one, such as `2.0.0-beta.1`. On GitHub a release can be marked as a pre-release, and then it is never shown as the latest release.
pre-sale: Selling a product before it is built: the customer pays now, the product starts on a stated date, and the money is returned in full if it does not. The strongest test of a solution, because it costs the customer something real.
pre-trade checklist: A short list of yes/no questions you answer before every trade, so the plan decides and not the mood.
precision and recall: Precision: share of predicted positives that are correct. Recall: share of actual positives that were found.
predatory pricing: Pricing below cost by a dominant firm to drive rivals out and raise prices later; an abuse of dominance under competition law. Not the same as an ordinary low price or a promotion.
premium: The amount you pay for an insurance policy, usually per year or per month, whether or not you ever claim.
prepayment discount: A lower price in exchange for paying earlier or for longer (an annual plan, a larger package); it buys cash and commitment and should be sized against what they are worth.
present value: What a future amount is worth today: the amount divided by (1 + discount rate) raised to the number of years.
pretexting: Getting information about a competitor by pretending to be someone you are not, for example booking a rival's sales call as a fake parent. It is dishonest and can be unlawful; public sources and your own customers give enough.
price anchor: The first price a buyer sees, which pulls their sense of what is expensive towards it. Honest anchors are real prices of real options; invented "was" prices are not.
price anchoring: Presenting a reference number before or next to your price so customers judge the price against it: for example, what the problem costs them today, or the monthly price next to a cheaper yearly one.
price ceiling: The highest price a buyer would accept before choosing their next-best alternative: what that alternative costs plus what our difference is worth to them. In this course, not a legal price cap.
price corridor: The range a price can sensibly sit in: from the floor below which a sale loses money to the ceiling above which buyers switch to their next-best alternative. The price itself is a choice inside it.
price elasticity: How strongly the quantity sold reacts to a price change: the percentage change in volume divided by the percentage change in price. Compare it with the volume a price change needs to keep the same contribution.
price fence: A rule that decides who gets which price or plan (student status, prepayment, a time of day, a usage limit). A good fence is real, easy to verify and respectful, and hard for others to cross.
price fixing: Competitors agreeing on prices, discounts or which customers each will serve, directly or through a third party; illegal under EU and Ukrainian competition law.
price indexation: Raising prices in line with a published measure of costs or inflation, on a stated schedule, so customers know the rule in advance.
price ladder: A test that offers the same thing at a sequence of real prices (to different people or over time) and records who actually buys at each step.
price positioning: Where an offer deliberately sits against its alternatives on price and benefit (premium, mid-market or economy), chosen on purpose rather than drifted into.
price skimming: Launching at a high price for the buyers who value the offer most, then lowering it step by step to reach wider groups, openly and without hiding what others paid.
price test: A controlled comparison of prices or offers (by cohort, time period or visitor group) designed to be fair and lawful: disclosed where needed, never personalized secretly, and judged on revenue and retention.
price waterfall: A step chart from the list price down to the realized price, showing how much each discount, code, refund and fee takes away.
price-increase notice: Telling existing customers in advance when and by how much a price will rise, why, and what they can do (buy at the old price until a date, switch plan, cancel).
price, volume and mix variances: A split of a revenue or margin change into the part caused by different prices, by selling more or fewer units, and by a shift between products with different margins.
pricing review: A regular (for example yearly) check of realized prices, the sales mix, discounts, competitors and costs, ending in a decision to hold, change or test prices.
pricing tiers: Several versions of a product at different prices, usually two to four, each aimed at a different kind of customer. Tiers let small customers start cheaply and larger ones pay more for more value.
primary metric: The one metric, chosen before launch, that a test's decision depends on.
primary metric (OEC): The single metric, chosen before launch, that decides whether a test wins.
principal component analysis (PCA): Rotates the data to new uncorrelated axes ordered by explained variance; a common way to reduce dimensions.
prior and posterior probability: The prior is what we believe before seeing the data; the posterior is the belief after updating on the data.
prioritization framework: An explicit, repeatable method for ranking themes or features against agreed criteria (value, effort, risk, confidence), so priority decisions can be explained and challenged instead of being made on gut feeling.
procurement: The function in a buying company that runs the purchase: it compares suppliers, negotiates price and terms, checks the contract and registers the new vendor. It often joins late and is measured on better terms, so expect requests to trade, not a signature on the first quote.
product analytics: The practice of measuring what people actually do inside a product, from the events they trigger, and turning those numbers into decisions about what to build, fix, price and grow.
product backlog: An ordered list of concrete work items (user stories, bugs, tasks) for the development team. It is an execution tool, far more detailed and short-lived than a roadmap.
product life cycle: The stages a product passes through, from launch through growth and maturity to decline or end of life. The stage shapes what the roadmap emphasizes and how far ahead it can sensibly plan.
product risk: Uncertainty about whether you can build the product and make it grow; conversations alone can't remove it, e.g. "I'll pay if you bring me customers".
product roadmap: A strategic communication tool that shows how a product will move towards its vision: which customer problems and business objectives the team will tackle, in roughly what order, and why. It states intent and direction, not a delivery contract.
product strategy: The chosen path from the product vision to results: which customers and problems to focus on, which bets to make and which objectives will show progress. The roadmap is how that strategy is sequenced and communicated.
product vision: A short statement of the future the product aims to create: who benefits, from what change, and why it matters to them and to the company. It is the anchor every roadmap item should trace back to.
product-market fit: The state in which a product satisfies a clearly defined market so well that customers buy, stay and recommend it with little pushing. It shows up in the numbers: sales get easier, churn falls and new customers arrive by word of mouth.
product-market fit: The state where a product satisfies a real market's need well enough that users keep using it and recommend it without being pushed. Seen in retention, not in sign-ups.
project: A temporary effort with a start, an end and a defined result, as opposed to ongoing operations. It ends when the result is accepted or when someone decides to stop it.
project board: A GitHub Projects view that shows issues and pull requests as cards in columns or as a table, for planning and tracking work.
project brief: A one-page description of a project that the sponsor and the team agree on: the goal, success criteria, what is in and out of scope, limits, assumptions and one named owner.
project buffer: One visible time reserve kept at the end of the project instead of padding every task. Tasks are estimated at their likely value, and the lead watches how fast the buffer is being used up.
project decision log: A dated list of the project's decisions: what was decided, by whom, which options were dropped and why. When a stakeholder asks why physics launches without a mobile app, the answer is a link, not a meeting.
project pre-mortem: A planning session where the team imagines the launch date has passed and the project has failed, and each person writes down why. The reasons go straight into the risk register with owners and triggers, so the exercise changes the plan rather than the mood.
project retrospective: A meeting at the end of a project or a stage where the team looks at what happened, why, and what to do differently next time. It is blameless: it asks what in the plan, process or information led to a result, not who to blame, and it ends with a few changes that have owners.
project risk: An uncertain event that, if it happens, changes the project's date, cost or result. Written as cause, event and consequence ("because…, … may happen, which would…"), it becomes specific enough to own and act on.
project sponsor: The senior person who needs the project's result, pays for it and makes the calls the project lead cannot: changing the goal, the budget or the fixed date. The sponsor answers for why the project exists; the lead answers for how it gets done.
project status report: A short regular written note on where the project really is against the plan: progress toward the next milestone, the forecast date, what is blocked, the top risks and what is needed from whom. A status color means something only when it comes with the forecast and the reason.
promotion mix: The combination of paid (ads), owned (your site, list, chats), earned (reviews, mentions, word of mouth) and shared (posts people pass on) tools you use, each chosen for the step of the path it has to move.
proof point: Evidence that makes a claim believable: a sample report, a guarantee, real reviews, numbers from your own data. Every differentiator needs at least one proof the customer can check.
proportion: The share of observations with a yes/no property; its standard error is sqrt(p(1 - p) / n).
proportional split: Sharing a couple's common costs so that each partner pays the same percentage of their own income.
psychological safety: A shared belief in a team that it's safe to ask questions, admit mistakes, raise bad news and disagree without being punished or embarrassed. It isn't the same as being nice or lowering standards: teams can have both high safety and high expectations.
pull request: A GitHub page that proposes merging one branch into another. It gathers the description, commits, changed files, automated checks and review discussion in one place.
pull-forward demand: Purchases moved earlier in time (for example, buying before an announced price rise) rather than new demand; it makes the months after the change look worse than they are.
purchasing criteria: The factors a customer actually uses to choose and pay for a solution; far more useful than a list of wished-for features.
push: Sending new local commits from a computer to the repository on GitHub. When you edit in the browser, GitHub saves the commit there directly.

Q

qualifying action: The action that makes a user count in a metric, such as opening the app or adding an expense. 'Any event' is rarely the right choice.
quality metric: A metric that shows how well the product works for each user or group it already has, such as retention, activation or expenses per active group. It should not move just because more users arrived.
quantitative (continuous) variable: A variable measured on a numeric scale where arithmetic makes sense, e.g. revenue or time on page.
quartile: One of three cut points (Q1, Q2 = median, Q3) that split sorted data into four equal parts.
quiet hours: Agreed hours with no expected replies, protecting focus and rest in a distributed team.

R

ramen profitability: The point where a young business earns just enough to cover the founders' basic living costs. It does not make anyone rich, but it removes the deadline set by the runway.
randomisation: Assigning units to groups by chance, so groups are comparable and confounders are balanced on average.
randomisation unit: The entity assigned to a variant (user, session, device, shop); analysis should be done at the same level.
range: The difference between the largest and the smallest value; very sensitive to outliers.
range estimate: An estimate given as a low and a high value with a stated confidence, such as "8 to 14 days, fairly sure", instead of one number. The width of the range shows how much is still unknown.
range role: The job each offer does in a range: an entry offer that brings customers in, a core earner that brings most of the contribution, a premium option and add-ons. Offers are judged by their role and their contribution, not by revenue alone.
rank: The position of a value in the sorted data; rank-based tests compare positions instead of raw values.
rate floor: The lowest rate a freelancer or solo tutor can charge per billed hour: target income plus business costs and taxes, divided by the hours that can really be billed in a year after preparation, admin, no-shows and quiet months.
ratio: One quantity divided by another, usually of a different kind: lessons per learner, LTV ÷ CAC. It says how many times one is the other and can be any positive number.
README: A file (usually `README.md`) that GitHub shows under the file list on the repository page. It explains what the project is and how to work with it.
real annual cost of credit: The yearly cost of a loan with all interest, fees and commissions included. It is the only fair way to compare loans; Ukrainian lenders must disclose it.
real interest rate: The growth of purchasing power: (1 + n) ÷ (1 + i) − 1, where n is the nominal rate and i inflation. 10.78% with 8% inflation gives 2.57%. The shortcut n − i always overshoots, more so when inflation is high.
real return: The return after inflation: how much more you can actually buy. Exactly, (1 + nominal) / (1 + inflation) − 1.
real return: A return after inflation: what your savings gain in purchasing power, (1 + nominal) ÷ (1 + inflation) − 1.
realized price: The average price actually received per unit after discounts, promo codes, refunds and payment fees; often well below the list price.
rearranging a formula: Turning a formula around to solve for a different quantity by doing the same operation to both sides, undoing the operations around the unknown in reverse order. From c·Q − F = 0 you get Q = F/c.
rebalancing: Bringing a portfolio back to its target mix by selling some of what grew and buying what fell behind.
rebase: Replaying a branch's commits on top of another branch as new commits, so history stays a straight line (`Rebase and merge` on GitHub).
recency effect: The tendency to give the latest events more weight than earlier ones, so the last weeks before a review outweigh months of steady work. A fact log kept through the whole period is the usual cure.
recognition: Noticing and naming a specific contribution, soon after it happens, in a form the person values. It costs little, but it works only when it is sincere, specific and fairly spread across the team.
recovery: The climb back to the previous peak after a drawdown; after a fall of d, the gain needed is 1 / (1 − d) − 1.
reference class forecasting: Estimating a new project from how long and how much similar past projects actually took, then adjusting for what is truly different. It corrects the optimism of building the plan only task by task.
reference price: The price a buyer compares ours with: what they paid before, what an alternative costs, or a price we show next to ours. A reference shown by a seller must be real.
referral: A new customer introduced by an existing one. Usually the cheapest and most trusted source, but limited by the size and goodwill of the customer base.
referral program: A system that rewards customers for bringing in new customers, often with a discount or free month for one or both sides. It works best when sharing the product makes the customer look good or helps them, not when it helps their competitors.
reforecast (re-planning from today): A new forecast of the finish date and cost made from where the project stands today: the work left, the people really available and the pace so far. What has already been spent is left out of the choice; only the road ahead counts.
refundable deposit: A small advance that reserves a place, counts toward the final price and is easy to get back. Because people pay something, deposits reveal willingness to pay better than survey answers.
regular investing (dollar-cost averaging): Investing the same amount at regular intervals whatever the price, which removes the need to guess the right moment.
regulated broker: A firm licensed by a financial regulator to hold and trade investments for clients, under rules on keeping client assets separate.
relative change: The change as a share of where it started: new ÷ old − 1, the same as (new − old) ÷ old. From 4% to 5% is +1 percentage point and a +25% relative change.
relative risk: The ratio of two probabilities, p₁ ÷ p₂. If 35% buy after a call and 25% without it, the relative risk is 1.40. The odds ratio from the same table, ad ÷ bc, sits further from 1 (here 1.62).
release: A published version of the product. On GitHub a release is a page built on a tag, with notes about what changed.
release plan: A tactical plan of which solutions ship when, with scope, dates and capacity. It answers "how and when" for work the roadmap has justified with "what and why".
relevant cost: A future cost that differs between the options being compared. Only relevant costs and revenues belong in a decision.
renewal: The point where a customer decides whether to continue a contract for another term. In B2B it is won or lost long before the date: through delivered results, a review with the budget owner and early notice of any price change.
rented channel: A channel you use on someone else's terms: a profile on a social network or a listing on a marketplace. Reach comes quickly, but the platform sets the rules, can take a fee and may own the relationship.
repeated-measures ANOVA: ANOVA for three or more measurements on the same subjects; removes between-subject variability from the error.
reporting time zone: The time zone that decides which calendar day an event belongs to. Logs are usually in UTC; a user's local day can differ, which changes daily metrics.
repository: A project folder together with its complete history of changes. On GitHub it has its own page with files, commits, branches and pull requests.
representative sample: A sample whose composition mirrors the population, so results generalise; random sampling helps achieve it.
reputation risk: A commitment where the customer stakes their name on you: introductions to peers or decision makers, a public testimonial or a case study.
request changes: A review verdict that asks the author to change something before merging. Shown as `Changes requested` in red.
request for proposals: A written request to several suppliers to propose how they would deliver defined work, compared on stated weighted criteria.
resale price maintenance: A supplier dictating the price, or a minimum price, at which partners or distributors must resell its product. Under EU and Ukrainian competition law it counts among the most serious restrictions, so it is never a legitimate sales tactic: a supplier may recommend a resale price or set a maximum one, and contract wording should be checked with a lawyer.
residual: Observed value minus the value predicted by the model.
resistance: A price area where sellers stepped in before, so a rise often stalls or turns there.
retention: The share of customers (or revenue) that stays over a period; for one month it equals 1 − churn. High retention is what makes a subscription business grow instead of refilling a leaking bucket.
retention plateau: The level where a cohort's retention curve stops falling: the users who stay for good. A plateau is a strong product-market-fit signal; a curve that keeps falling to zero is a warning.
retention rate: The share of users who are still active after a given period, e.g. day-30 retention.
return on marketing contribution: The incremental contribution a campaign brought minus its cost, divided by its cost. Unlike a return calculated on revenue or on all sales, it shows whether the spend actually paid for itself.
return on marketing investment (ROMI): Incremental margin from a marketing activity minus its cost, divided by its cost. Computed on revenue instead of margin, or on all growth instead of growth above the baseline, it flatters every campaign.
revealed willingness to pay: Willingness to pay measured by behavior (a purchase, a pre-order, a deposit, a click on a real price) rather than by an answer to a question; stated answers are a range, not a demand curve.
revenge trading: Trading bigger or faster right after a loss to win it back, usually breaking the plan.
revenue: What the company earned from its own sales in a period, recognized when it delivers what was paid for. For a marketplace acting as an agent this is its commission, not the whole amount the customer paid.
revenue churn: The share of MRR lost in a period to cancellations and downgrades: lost MRR ÷ MRR at the start. It can differ a lot from customer churn when customers pay different amounts.
revenue per visitor (RPV): Revenue divided by the number of visitors who saw the price; it combines conversion and price, so a higher price can win on it while converting worse.
revenue recognition: The rules for when money from a sale becomes revenue: when the promised lesson or service period is delivered, not when the customer pays.
reversible decision: A decision that can be undone cheaply if it turns out wrong, such as a trial shift pattern. Reversible decisions can be made fast and close to the work; irreversible ones (letting a contract lapse, a hire) deserve more options, input and time.
revert: A new commit that undoes an earlier one. History keeps both, so nothing is erased. GitHub offers a `Revert` button on merged pull requests.
reward-to-risk: How much you aim to gain for each unit you risk; 3 to 1 means a target three times as far as the stop.
RICE scoring: A prioritization formula that scores each idea as Reach × Impact × Confidence ÷ Effort, giving a comparable number for how much value it delivers per unit of work.
right censoring: Users who entered recently haven't had the full window to convert yet, so their conversion looks lower than it will be. Recent cohorts must be excluded or marked incomplete.
risk capacity: How much loss your finances can absorb without harming your goals, set by horizon, income stability and savings.
risk exposure: Probability times impact, where the impact is in days or money: a 30% chance of losing 10 days is an exposure of 3 days. It helps rank risks, but a rare risk that would sink the project needs a response even when its exposure looks small.
risk of ruin: The chance that a losing run empties the account so far that it cannot recover.
risk owner: The person who watches one risk, notices when it starts to happen and starts the agreed response. The owner does not have to fix everything alone, but nobody else is waiting for someone to notice.
risk per trade: The amount you lose if the stop is hit, usually stated as a small share of the account.
risk register: A short shared list of the project's risks, each with probability, impact in days or money on a written scale, an owner, a trigger and the chosen response. A dozen live risks with owners beat a long list nobody reads.
risk response: What the project decides to do about a risk: avoid it by changing the plan, transfer it to someone better placed (an insurer or a contract), reduce its probability or impact, accept it with a reserve, or escalate it to the sponsor when it is beyond the project's authority. A response that breaks the law, safety or data-protection rules is not an option.
risk tolerance: How much loss you can live with emotionally without abandoning your plan.
risk trigger: An observable early sign, agreed in advance, that a risk is turning real and the response should start, for example fewer than six tutors confirmed by 15 December. A trigger turns "keep an eye on it" into a date and a number.
risk unit: The planned risk of one trade used as a measuring stick: for a 10,000 account at 1% risk, one risk unit is 100 dollars.
roadmap alignment: A shared understanding among stakeholders of where the product is going, why, and what their part is. Aligned people can disagree on details yet act in the same direction; alignment does not require consensus.
roadmap co-creation workshop: A structured session in which key stakeholders build or finalize the roadmap together, typically covering hopes and fears, vision and goals, working back from the desired future, and sizing and prioritizing themes.
roadmap disclaimer: An explicit note that the roadmap reflects current plans and may change without notice. It protects the team from accusations of broken promises and warns customers not to base purchases on future items.
ROI case: A short calculation, made with the buyer, of what a purchase returns to them over a stated period: the gain or saving minus the total cost of ownership, using their numbers and named assumptions. It is written for the person who signs the budget, usually the finance director.
rolling forecast: A forecast updated every month or quarter that always looks the same distance ahead, instead of a fixed annual budget that goes stale.
rolling period: Every window of a fixed length in a history, each starting one step later, used to see how often an outcome happened.
rolling retention: The share of a cohort active on day N or any later day. It is always higher than day-N retention and keeps changing as new data arrives.
rounding down (floor): Taking the largest whole number that is not more than x, written ⌊x⌋: ⌊34.5⌋ = 34. Used when you count what fits: full groups, whole packages a budget buys.
rounding error: The gap between a result computed from rounded inputs and the same result from unrounded ones. It grows when you divide by a rounded number or subtract two rounded numbers.
rounding up (ceiling): Taking the smallest whole number that is not less than x, written ⌈x⌉: ⌈5,949.3⌉ = 5,950. Used whenever you need enough of something: break-even units, staff, servers, test length.
rules for honest answers: A set of rules for asking questions so that even someone who wants to please you (a friend or relative, say) can't give you misleading answers: talk about their life, ask about past specifics, listen more than you talk.
runbook: A short written procedure for a recurring or urgent situation, such as what to do when a live lesson is hit by an outage.
running total: A sum whose upper limit moves: Sₖ = x₁ + … + xₖ. Margins of 120, 100 and 90 give running totals of 120, 220 and 310. LTV curves and payback use it.
runway: How many months the founders or the business can keep going before the money runs out, at the current level of spending and income. Usually calculated as available cash divided by the net monthly burn.

S

SaaS (software as a service): Software that customers use online and pay for with a regular subscription instead of buying and installing it once.
safe bucket: Money for the next few years of spending kept in cash or short government bonds, so a fall in stocks never forces a sale at the bottom.
sales cycle length: How long it takes a deal to go from the first qualified conversation to a signed contract, usually measured as a median in days. Committee purchases, procurement and security reviews make it longer, and a plan that ignores this runs out of time.
sales forecast: An estimate of what will be signed or billed in a period, built bottom-up from existing accounts, named open deals and a realistic allowance for new ones. A stuck deal counted at full value is the most common way a forecast lies.
sales objection: A concern a buyer raises that stands between them and a yes, such as price, timing, risk or a competitor. Handled honestly, it is information about what the deal is missing, to be clarified and answered with a fact or a trade.
sales pipeline: The list of open deals arranged by stage, from first qualified conversation to signed contract, with a value and an expected close date for each. It is only useful when every stage is defined by something the buyer did, not by how the seller feels.
sales-qualified lead (SQL): A lead that a seller has checked and accepted as worth active selling time, by a definition marketing and sales agreed on together. Counting leads without this shared definition lets each side report a different funnel.
SAM (serviceable available market): The part of the total market that your product and sales channels can actually serve, for example only shops in regions and segments you can reach.
sample: The subset of the population that we actually observe or measure.
sample ratio mismatch (SRM): Variant sizes that differ from the planned split more than chance allows. It usually means a bug in assignment or logging, and the test result can't be trusted until it's explained.
sample ratio mismatch (SRM): When the observed split between groups differs significantly from the planned one (e.g. 50/50); signals a broken experiment.
sample size: The number of observations (per group in a test); planned in advance from alpha, power, baseline and MDE.
sampling bias: A systematic difference between sample and population caused by how observations were selected.
sampling distribution: The distribution of a statistic (e.g. the mean) across many hypothetical samples of the same size.
sanity check: Comparing a computed result with a quick estimate or a known limit (a margin can’t exceed the price, a share can’t exceed 100%) before you trust it.
saturation: The point where new conversations with a segment stop producing new information; often after 3–5 talks with a well-defined segment.
saving: Keeping money safe and available for near-term needs, with little or no risk and a return close to inflation.
saving rate: The share of income not spent on essentials or flexible spending over a period: (income − spending) ÷ income.
scale and stop rules: Thresholds agreed before a month starts that decide when a channel gets more budget and when it is cut back to a test level, so decisions don't depend on mood.
scary question: An important question you instinctively avoid because the answer might hurt the idea (price, budget, legal blockers); every conversation should include at least one.
scatter plot: A chart with one point per observation, placed by the values of two quantitative variables.
scenario analysis: Building several consistent versions of the future (for example base, weak and strong), each with its own set of assumptions, and comparing the results.
scope: Everything a project has agreed to deliver, written as an explicit in / out list. Whatever is not on the in list is out until someone decides otherwise.
scope creep: The slow growth of a project's scope through small additions that nobody decided on as a change, so the date and the budget stay the same while the work grows.
scree plot: A plot of eigenvalues by factor number; factors after the 'elbow' are dropped (Cattell's criterion).
seasonal index: A month’s value divided by the average month: 9,620 lessons in a year that averages 7,400 a month gives an index of 1.30. Dividing by the index removes the season.
seasonal index: A month's value divided by the average month of the year. Twelve monthly indices average 1, so an index of 0.6 means a month runs at 60% of a typical one.
seasonal reserve: Money saved in good months for a dip in income that comes every year, such as a thin summer, kept apart from the emergency fund.
seasonality: A repeating pattern tied to the calendar, such as weekday effects or holiday peaks.
secondary metric: A metric read to explain a test result, never to decide it.
security questionnaire: A list of questions a buyer's IT or security team sends a vendor about how it stores, protects and processes their data: access, encryption, backups, subcontractors, incident response. Accurate answers kept ready shorten the deal; guesses come back later as blockers.
segment attractiveness: How worth winning a segment is on its own: its size, growth, how much contribution a customer brings, how seasonal it is and how contested. Judged next to your ability to win, never alone.
segmentation: Splitting users or customers into groups that behave differently, so each can be targeted differently.
segmented pricing: Charging different groups different prices behind real, verifiable fences (students, siblings, regions, time of purchase). Lawful and common; abuse of dominance, collusion and unfair consumer practices are not.
selection bias: A difference between groups created by who ends up in each group, not by the thing being compared. 'Users who use receipt scanning retain better' is a classic case.
self-assessment: The person's own view of their results, collected before the lead shares an evaluation.
self-funding: Paying for a new business with the founders' own money, such as savings or a personal loan, instead of selling a share to investors.
semantic versioning: A version format MAJOR.MINOR.PATCH: breaking changes raise MAJOR, new features raise MINOR, fixes raise PATCH.
sensitive personal traits: Personal characteristics such as ethnicity, religion, health, political views or sexual orientation, which data-protection law guards closely. As a house rule, segments and ad targeting are never built on them; separately, EU platform rules bar platforms from showing profiling-based ads to users they know are minors.
sensitivity analysis: Changing one assumption at a time to see how much the result moves, to find the assumptions a decision really depends on.
sequence risk: The risk that bad returns arrive right when you start withdrawing, which hurts far more than the same returns later.
sequential testing: Test designs with adjusted thresholds that allow valid interim looks at the data.
server-side event: An event logged by the backend rather than by the app on the user's device, for example a recurring bill created automatically. It can happen without the user doing anything.
setting expectations: Agreeing out loud, early and in both directions, what good work looks like, what the lead will do and what the team can count on. Most later conflict between a lead and a report starts with expectations nobody stated.
settle-up: A payment that clears a debt between two members of a Halves group. The payer records it and the receiver confirms it, so one settle-up can appear as two events.
share: A part divided by the whole it belongs to, so always between 0 and 1 (0% and 100%): paying users out of all users, contribution margin out of the price.
share: A small ownership slice of a company that can be bought and sold; its price moves with the company's prospects and with mood.
short position: A trade that profits when the price falls: you sell borrowed units first and buy them back later; losses are not capped.
shuttle diplomacy: Building alignment by meeting stakeholders one-on-one before any group session: learning each person's goals and constraints, scoring their ideas against shared objectives and bringing a pre-negotiated draft to the room.
sigmoid function: The S-shaped function p = 1 ÷ (1 + e⁻ᶻ) that turns any score z into a probability between 0 and 1; z = 0 gives 0.5. It is the inverse of z = ln(odds).
sign test: Compares the number of positive and negative before-after changes, ignoring their size.
significance level (alpha): The threshold for rejecting H0, fixed before the test, usually 0.05; equals the accepted false-positive rate.
significant figures: The digits of a number that carry information, counted from the first non-zero digit. 7,840 to one significant figure is 8,000; to two, 7,800.
similar-to-me bias: Rating people higher when they resemble the evaluator in background, style or habits, regardless of results. Agreed criteria, written evidence and a second reviewer reduce it.
simple interest: Interest charged only on the original amount: I = P × r × d ÷ 365, with r the yearly rate and d the number of days. The same amount accrues every day; nothing is charged on earlier interest.
Simpson's paradox: A trend that appears in every subgroup reverses when the groups are combined, because group sizes differ.
single tax: The simplified tax a Ukrainian sole proprietor pays instead of income tax: a fixed monthly amount in some groups or a share of income in others.
sinking fund: Saving a little every month for a known future cost, such as a holiday or car repair, so it doesn't land on a card.
skewed returns: A spread of results in which a few very large winners pull the average far above the typical result.
skewness (skewed distribution): Lack of symmetry in a distribution; with a long right tail (typical for revenue) the mean is above the median.
slippage: A deal's expected close date moving to a later period, often more than once.
slippage: The difference between the price you expected and the price you actually got, common in fast or thin markets.
slope (regression coefficient): b1: how much the predicted outcome changes when the predictor increases by one unit.
slope of a line: The b in y = a + b·x: how much y changes when x grows by one unit. Between two points it is Δy ÷ Δx.
social discount: A lower price offered to people in a hard situation (for example displaced people or veterans), with a fence that is simple and dignified to use.
social engineering fraud: Fraud that tricks people into giving codes, card details or money, for example a fake call from "the bank's security service".
solution validation: Checking, before building a product, that a proposed way of solving the problem fits the customers' real workflow, beats what they use now and does not create new problems.
SOM (serviceable obtainable market): The share of the serviceable market you can realistically win in the next few years, given competition and your own capacity. It is the number to compare with your revenue goal.
SOP (standard operating procedure): A written, step-by-step description of a recurring task, with the reason behind it and known pitfalls, detailed enough that someone new can do it without asking the founder.
span of control: The number of people who report directly to one manager. There is no single right number: it depends on how similar the work is, how experienced the people are and how much time the manager has for one-to-ones.
Spearman rank correlation (rho): Pearson's r computed on ranks; captures monotonic relationships and is robust to outliers.
speculating: Buying something mainly in the hope that someone will pay more for it soon, without relying on the income the asset produces.
spending plan: A plan for the month that splits income into essentials, saving and flexible spending, including money for things you enjoy. Unlike a strict budget, it is meant to be lived with.
spike investigation: Explaining a sudden jump or drop in a metric by listing possible causes (tracking, traffic, product, outside events) and ruling them out one by one with the data already available.
spread: The gap between the ask and the bid; every round trip starts this much in the red.
squash merge: Merging a pull request as one new commit on the target branch that contains all its changes (`Squash and merge` on GitHub).
stage entry criterion: A buyer action that must have happened before a deal may be moved to a stage.
stage of development: A label showing how far a roadmap item has progressed, e.g. discovery, design, in development, beta, released. It tells stakeholders what is still an open problem and what is already a concrete solution.
stakeholder: Anyone who influences whether your product gets bought or used, such as users, buyers, IT, legal or partners; missing one can quietly block a deal.
stakeholder (roadmap stakeholder): Anyone inside or outside the company who shapes, funds, builds, sells, supports or depends on the product and so has a stake in the roadmap: executives, sales, marketing, support, engineering, finance, partners and customers.
stakeholder map: A one-page picture of everyone the project affects or depends on, placed by how much they can influence it and how much the result matters to them. It shows whom to involve closely, whom to keep informed and whom nobody has talked to yet.
stale deal: An open deal with no real buyer action for a long time; it should not count at full value in a forecast.
stalling (brush-off): A polite way of ending the conversation without committing: "Keep me posted", "Let me know when it launches", "Don't call us, we'll call you".
stand-up meeting: A short, regular team check-in, usually daily and 10–15 minutes, to surface blockers and coordinate the day. Status that can be read in writing doesn't need it; once it grows long, the problem-solving belongs in a separate, smaller conversation.
standard deviation: A measure of how widely returns spread around their average; a common number for volatility.
standard deviation (SD): The square root of the variance; spread expressed in the same units as the data.
standard error (SE): The standard deviation of a statistic's sampling distribution; for a mean it is SD / sqrt(n).
standardisation (scaling): Converting variables to z-scores so that variables on large scales do not dominate distances.
starter cushion: A first, small emergency fund, enough to pay for one typical surprise such as a broken appliance without borrowing, built before the full cushion of several months.
state pension: The pension paid from the solidarity system to people who reach retirement age with enough years of insurance record.
static vs dynamic model: A static model describes a state at one moment; a dynamic model describes change over time.
statistic (estimate): A number computed from a sample that estimates a population parameter, e.g. the sample mean.
statistical power: The probability that a test detects a real effect of a given size; 1 - beta, usually planned at 0.8.
statistical significance: A result is significant when p < alpha; it says the effect is unlikely to be pure noise, not that it is large or important.
status checks: Automated jobs (tests, builds, linters) that run on a pull request's commits and report passed, failed, pending or skipped.
step conversion: Users who reached a funnel step divided by users who reached the previous step. Multiply step conversions to get the whole funnel.
step cost: A cost that stays flat over a range of volume and then jumps to a new level, such as one more support coordinator for every few hundred learners.
stepwise regression: Builds a model by adding or removing predictors one at a time based on their contribution.
stickiness: DAU divided by MAU (or WAU by MAU): the share of monthly users who show up on a typical day or week. Only meaningful at the product’s natural usage rhythm.
stock and flow: A stock is an amount at a moment (subscribers, MRR, cash); flows change it over a period. End = start + inflows − outflows.
stop order: An order that becomes a market order once the price reaches a trigger level, often used to exit a losing trade.
stop-loss: A pre-set exit price that closes a trade at a limited loss, placed where the trade idea is wrong.
strategic buyer: A buyer, often a larger company in a related market, who acquires a business for its customers, technology or position and is likely to change the product and ask the founders to stay on.
stretch assignment: A task slightly beyond what the person has done before, given on purpose with support and a safe way to fail. It is one of the fastest ways people build new skills at work.
structural conflict: A conflict caused by how work is set up rather than by personalities: overlapping roles, shared resources, goals or metrics that pull people in different directions. Fixing the setup usually helps more than talking to the people about their attitude.
Student's t-test (independent samples): Compares the means of two independent groups: t = (mean1 - mean2) / SE of the difference.
subscription creep: Small recurring payments that pile up unnoticed until together they cost more than one noticeable purchase.
subtheme: A narrower need within a theme. Subthemes split a broad problem into parts the team can explore separately, and they are also where a known or likely solution can be noted without losing the "why".
success criteria: The checks that say whether a project worked, written before it starts. Useful ones have two parts: what must be delivered by when, and what must change for the users or the business afterwards.
suggested change: A review comment that proposes exact replacement text for a line. The author can apply it with one click (`Commit suggestion`).
sum of squares: The sum of squared deviations from the mean, Σ(xᵢ − x̄)². For 6, 9, 4, 7 and 14 it is 58. Divided by n − 1 it gives the variance; in ANOVA it splits into between and within parts.
sum sign (Σ): The Greek capital sigma, meaning "add up": Σ with i = 1 below and n above adds x₁ + x₂ + … + xₙ. The term after it says what to add; the limits say which terms.
sunk cost: Money already spent that no decision can bring back. It must not influence the choice about what to do next.
support: A price area where buyers stepped in before, so a fall often slows or turns there.
survivorship bias: An error that comes from looking only at funds or companies still alive, which flatters the average because the failures dropped out.
survivorship bias: Judging a group by the winners that remain while the failures that disappeared are left out.
synthesis: Combining notes from several conversations into patterns and decisions, rather than acting on any single customer's words.
synthetic persona: A customer profile generated by an AI tool. Useful for drafting questions and hypotheses, never a substitute for talking to real customers or reading your own data.

T

T-shirt sizing: A quick, relative effort estimate using sizes XS, S, M, L and XL (often mapped to 1–5) instead of days or story points. It is precise enough for prioritizing without implying a schedule.
table stakes: Features every serious alternative offers, such as qualified teachers or learning from home. You must have them to be considered, but leading with them gives customers no reason to choose you.
tag: A permanent name attached to one commit, most often a version number such as `v2.4.0`.
tailored demo: A product demonstration built around the problems the buyer named in discovery: it shows only the parts that solve them and ends with an agreed next step. The opposite is a generic tour of every feature.
TAM (total addressable market): The total yearly revenue available if every potential customer of the kind you serve bought your product: number of potential customers × yearly price.
target floor: The cost floor plus the contribution the same scarce capacity (tutor hours, a teacher's evenings) would earn in its best other use. Below it, a deal loses money once you count what you give up.
target segment: The segment you deliberately serve first and shape your offer, message and channels around. Choosing it also means writing down whom you won't serve for now.
task conflict and relationship conflict: Task conflict is disagreement about the work itself (what to do, how, in what order); relationship conflict is personal friction. Research finds that both often go together and both can hurt results; task disagreement helps mainly when trust is high and it stays about the work.
task owner: The one named person who answers for a task being finished, even when several people work on it. A task with two owners or a team as its owner usually has none, so every line of the plan gets exactly one name.
tax discount: A yearly claim that returns part of the personal income tax paid on salary for certain spending, such as own contributions to a voluntary pension fund, within limits set by law. Who can use it and the limits change; check the current rules.
tax drag: The part of the return lost each year to taxes on dividends or gains while the money is invested.
tax set-aside: Moving the state's share of each payment to a separate tax account the day it arrives, so the taxes for a period are already there when they are due.
tax-equivalent rate: The rate a taxed option would need before tax to leave you the same as a tax-free one: the tax-free rate divided by (1 − tax rate).
team capacity: The amount of work a team can handle in a period, for example hours per week that coordinators can spend on tickets.
team lead role: The job of getting results through a team rather than through your own work: a lead is judged by what the whole team delivers, so time moves from doing tasks to setting direction, removing blockers and growing people.
team structure: How work and responsibility are divided inside a team: by subject, by channel, by customer group, or with rotating shared roles. A good structure keeps hand-offs few and clear and leaves each person a piece of work they can own.
term deposit: Money placed with a bank for a fixed period at a fixed rate. Taking it out early usually costs part of the interest, and some deposits cannot be closed early at all.
term life insurance: Insurance that pays a sum to the insured person's dependants if they die within the term. It protects the family and is kept separate from saving.
test assumptions: Conditions a test needs to be valid, e.g. independent observations, approximate normality, equal variances, no extreme outliers.
test statistic: A number computed from the data (t, U, F, chi-square...) that is compared with its distribution under H0.
theme (roadmap theme): A high-level customer need, problem or job that groups related work on the roadmap, phrased as a result rather than a solution, e.g. "make reordering effortless for regular buyers".
three-point estimate: An estimate built from an optimistic, a most likely and a pessimistic value. It is useful only if you keep the spread: reporting just the weighted average hides how late the work could be.
tiered rate: A rate that changes by slices of the base, each rate applying only to its own slice, as in a commission of 10% up to 100,000 and 15% above. It has an effective rate (total ÷ base) and a marginal rate (on the next unit).
time commitment: Investing real time in your solution: a follow-up meeting with clear goals, reviewing wireframes, or using a prototype for a meaningful period.
time series: Observations of a metric ordered in time, e.g. daily orders; often has trend and seasonality.
time to value: How long it takes a new user to reach activation. Shorter is usually better, and a median tells more than a mean here.
time under water: How long a portfolio stays below its previous peak before it gets back to it.
time value of money: A hryvnia today is worth more than a hryvnia next year, because it can be invested or used now and because future money is uncertain.
time window: The period a metric covers, such as one calendar day or seven days ending yesterday, together with the time zone that decides where each day starts.
time-and-materials contract: A contract that pays for the hours actually worked at an agreed rate, plus materials, so the client carries the risk of the scope growing. It suits work whose scope is still unclear, provided there is a cap and a regular check of what was delivered.
time-weighted return: A fund's return that ignores when money came in or went out; it measures the fund, not the investor.
timeframe: The period each candle covers, such as a day or an hour; the same market looks different on each.
timeframe (time horizon): The broad time bucket a roadmap item sits in: a quarter, a half-year, or Now / Next / Later. Broad buckets show sequence and urgency without promising exact ship dates.
total cost of credit: Everything paid on a loan minus the money received: interest, every fee and any insurance required to get it.
total cost of ownership: Everything a purchase costs the buyer over its life, not just the price: setup, staff time, training, integration, support and, later, switching away. Comparing offers on total cost rather than price often changes which one is cheaper.
total price: The final amount a consumer pays, including taxes and every unavoidable fee, and per billing period for a subscription; it must be shown before the buyer commits.
tracking difference: The gap between a fund's return and its index's return over a period; it shows the real cost better than the headline fee.
tracking plan: A document that lists the questions a feature must answer, the events and properties needed to answer them, where each is logged and how it will be checked before launch.
trade journal: A record of every trade with its reason, size, stop, result and whether the plan was followed.
trade-off table: A table that lists the options against the criteria that matter, so that options worse than another on every point can be dropped.
trading: Buying and selling an asset over days, hours or minutes to profit from price moves, as opposed to holding it for years.
trading plan: A written set of rules for what you trade, when you enter, where you exit, how big you go and when you stay out.
trading range: A stretch where price moves sideways between a floor and a ceiling without a clear trend.
traffic mix: The shares of new users from each source (invites, store search, paid ads, partner promos). When the mix changes, averages change even if nothing in the product did.
train/test split (holdout): Fitting a model on one part of the data and evaluating it on unseen data to estimate real performance.
treatment (experimental) group: The group that gets the change being tested (the variant).
trend: A sustained move of price in one direction, seen as higher highs and higher lows in an uptrend.
trial-to-paid conversion: The share of users who start a free trial and then make a first payment.
triggered enrollment: Counting a user in a test only when they reach the point where the variants differ, such as opening the paywall. It removes users the change can't affect.
trimmed mean: The mean computed after dropping a fixed share (e.g. 5-10%) of the smallest and largest values.
truncated axis: A value axis that does not start at zero; it exaggerates small differences in bar charts.
trunk-based development: A way of working where everyone merges small changes into the main branch at least once a day, with very short-lived branches or none at all. Unfinished work is hidden behind feature flags.
Tukey's HSD test: A common post hoc test comparing all pairs of groups when variances are equal.
two-proportion z-test: Compares two conversion rates using the normal approximation: z = (p1 - p2) / SE of the difference.
two-way (multifactor) ANOVA: ANOVA with two or more factors that tests each main effect and their interaction.
type I error (false positive): Rejecting a true H0: declaring an effect that does not exist. Its probability is alpha.
type II error (false negative): Failing to reject a false H0: missing a real effect. Its probability is beta.

U

UCITS fund: A fund set up under the EU framework for retail investment funds, with rules on diversification, custody and disclosure.
unified social contribution (ESV): The mandatory social contribution that funds the state pension and counts toward a person's insurance record.
unique users: The number of distinct people who did something in a period, however many times each did it. Compare with the event total.
unit counted: What a metric counts: distinct users, distinct groups, events or settlements. Changing the unit changes the number even on the same data.
unit economics: The revenue and costs of one unit of the business, usually one customer: what it costs to win them, what they pay, what it costs to serve them and how long they stay. It shows whether each new customer makes the business richer or poorer.
upward feedback: Feedback that reports give to their manager. It works when the lead asks a narrow question, listens without defending, thanks the person and later shows what changed.
US estate tax for non-US persons: A US tax that can apply when a non-US person dies holding US-situs assets, such as shares of US-domiciled funds, above a small threshold.
user churn: Users who stop using the product. For free products it is inferred from inactivity, so its definition (how long inactive) must be stated.
user journey map: A step-by-step picture of how a person solves a problem today, from noticing it to moving on, often with their feelings at each step. Painful steps are candidates for roadmap themes.
user property: A detail about the user that holds across events, such as sign-up date, platform or acquisition channel. Used to segment users.
user, payer and influencer: The different people behind one purchase: the user who studies, the payer who decides and pays, and the influencers whose advice they trust (a teacher, a friend). When these are different people, each needs a different message.

V

valuation multiple: The number by which a financial figure, such as ARR or yearly profit, is multiplied to estimate a company's price. It goes up with growth, low churn and independence from the founder, and down with risks.
value interview: A conversation about a buyer's past behavior around a problem: what they tried, what they spent, what the problem costs them. It asks about facts, not "would you pay".
value map: A chart that places offers by the benefit buyers perceive against their price; offers above the market line are overpriced for what they give, those below it are under-priced.
value metric: The unit that grows when a customer gets more value from the product, such as bookings or cars served per month. Tying prices or plan limits to it lets revenue grow together with customer success.
value metric: The unit a price is charged per (per lesson, per month, per practice minute, per result), ideally one that grows with the value the buyer gets and with the cost of serving them.
value proposition: A concise statement of who the product is for, which need it meets, what benefit it delivers and how it differs from the alternatives. It is often written with a fill-in template (For… who… the… is a… that… unlike…).
value vs effort scorecard: A scoring method that rates each item's contribution to customer needs and business objectives, divides the total by estimated effort and often multiplies by confidence: priority = value ÷ effort × confidence.
value-based pricing: Setting a price from the buyer's next-best alternative plus the value of the difference, so the buyer keeps part of the value and the business captures the rest; costs only check the floor.
vanity metrics: Numbers that look impressive and usually only go up, such as total downloads or sign-ups, but don’t tell the team whether users get value or what to do next.
variable: A measurable property of each observation, such as order value, session length or whether a user converted.
variable cost: A cost that grows with every unit sold or delivered, such as a tutor's payout per lesson or a payment fee per purchase.
variance: The average squared deviation from the mean; the sample version divides by n - 1. Measured in squared units.
variance analysis: Comparing actual results with the plan and splitting the difference into its causes, such as price, volume, mix and currency.
venture capital: Money from professional investors who buy a share of a young company and expect very fast growth, because they count on a few big winners to cover many failed bets.
verbatim quote: A customer's exact words written down in quotation marks; useful as evidence for the team and as language for marketing.
version control: A way of keeping every saved state of a project, with who changed what, when and why, so any earlier state can be viewed or restored.
vesting: Earning your shares in a company gradually over time, usually over three or four years, instead of owning them all on day one. If a founder or employee leaves early, the shares they haven't earned yet go back to the company.
viral coefficient (k-factor): The number of new users each user brings on average: invitations per user × share of invitations that turn into new users. Below 1, virality amplifies other channels but can't drive growth alone.
viral cycle time: The time from a user joining to the users they invited joining. Shorter cycles make the same k grow much faster.
volatility: How much and how often an investment's value goes up and down.
volatility: How much an investment's value swings up and down. Higher expected returns come with bigger swings.
volatility: How much price typically moves in a period; wider swings call for wider stops and smaller sizes.
volume: How many units changed hands in a period; a rough sign of how many people took part in a move.
volume metric: A metric that counts how much: users, groups, expenses or revenue in total. It can rise because of ad spend or a season while the product itself gets no better.
voluntary pension fund: A private fund where a person or employer adds to retirement savings on top of the state pension.

W

warm intro: An introduction through someone both sides trust, which gives you instant credibility; the main source of good conversations after the first few.
weekly active groups: Distinct groups in which at least two members added an expense (not server-created) or recorded a settle-up in the week; the north star metric of Halves in this course.
weighted mean: A mean in which each value counts in proportion to its weight, e.g. average conversion across segments weighted by traffic.
weighted score: The sum of each criterion’s score times its weight, with the weights adding to 1: Σwᵢsᵢ. Scores 4, 3 and 5 under weights 0.5, 0.3 and 0.2 give 3.9.
weighted scoring: Rating options on several criteria, multiplying each rating by a written weight and adding them up. Each criterion states which direction is good (for competition, a higher score means less of it), because one criterion scored the wrong way can flip the ranking.
Welch's t-test: A version of the two-sample t-test that does not assume equal variances; a safe default.
whipsaw: Quick back-and-forth moves in a range that trigger signals and then reverse them, producing a string of small losses.
who-where pair: A segment described as a specific group plus a place (physical or online) where you can reliably find them; if you can't name the "where", keep slicing.
Wilcoxon signed-rank test: The non-parametric alternative to the paired t-test: ranks absolute differences and compares sums for positive and negative shifts.
willingness to pay (WTP): The highest price a particular buyer would pay for an offer. It differs between buyers and situations, and what people do reveals it better than what they say.
Wilson interval: A confidence interval for a share whose centre is nudged toward 50% and whose width uses √(p(1 − p)/n + z²/4n²). It behaves better than p ± z·SE for small samples and rates near 0 or 1.
win rate: The share of closed opportunities that were won, counted over a period on deals that reached a decision. Pooled across all deals it can differ a lot from an average of per-seller rates, so the method has to be stated.
win rate: The share of trades that end in profit; it says nothing alone without the size of wins and losses.
withdrawal rate: The share of a portfolio taken out each year to live on; a higher rate makes running out of money more likely.
withholding tax: Tax taken from dividends or interest by the country where they are paid, before the money reaches the investor.
within-group variance: The variability of observations around their own group mean; the 'noise' in ANOVA.
word of mouth: Customers telling other potential customers about a product on their own, in conversation, chats or communities. In a close-knit niche it is often the cheapest and most trusted way new customers arrive.
work breakdown structure: A tree that splits a project's result into deliverables and then into pieces of work small enough to estimate and give to one owner. It is built from what must be handed over, not from a list of activities.
work in progress limit: A cap on how many tasks a person or a column of the task board may have started but not finished. Starting less makes work finish sooner and shows where it piles up.
workaround: A makeshift way a customer already copes with a problem (spreadsheets, interns, manual steps); a strong sign the problem is real and a benchmark for price.
working agreement: A short written set of rules the team agrees on together: response times, which channel is for what, when people are reachable, how hand-offs and absences work. The team reviews it when it stops matching how work actually happens.
working capital: Money tied up in day-to-day operations: what customers owe you plus other current assets, minus what you owe suppliers and customers who prepaid. Prepayments can make it negative, which funds growth.
written status update: A short written update (what changed, what is blocked, what is needed) that replaces a status meeting.
WSJF (weighted shortest job first): A sequencing rule that divides cost of delay by job size and takes the highest ratio first, so short, urgent, valuable items ship before long items of similar value.

Y

year-over-year comparison: Comparing a month with the same month a year earlier, so that seasonal swings (a summer dip, a September restart) don't look like growth or decline.

Z

z-score (standard score): How many standard deviations a value is from the mean: (x - mean) / SD.
zombie lead: A prospect who keeps taking meetings and saying nice things but never commits or says no; they keep you in the friend zone and waste your time.
zooming in too early: Jumping into details of a specific problem before checking that the person cares about that area at all; it produces plausible but misleading answers.