Intermediate Vocabulary #growth#aarrr#ab-testing#metrics

Growth Engineering Vocabulary

5 exercises — Practice the terms growth engineers use every day: AARRR metrics, experimentation, engagement, viral growth, and conversion funnels.

Core Growth Engineering vocabulary clusters
  • AARRR funnel: acquisition, activation, retention, revenue, referral
  • Engagement: DAU, MAU, DAU/MAU ratio, engagement rate, feature adoption
  • Experimentation: A/B test, holdout group, treatment group, statistical significance, uplift
  • Strategy: North Star metric, growth loop, viral coefficient, conversion funnel
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A growth PM presents the AARRR framework to new team members:
"We track five stages — Acquisition, Activation, Retention, Revenue, and Referral. Right now our biggest leak is between the first and second stage: users sign up but never reach their aha moment. We need to fix that before spending more on paid ads."
Which AARRR stage is described as the moment a user first experiences the core value of the product?

Vocabulary Reference

Key growth engineering terms and their definitions.

AARRR (Pirate Metrics)
A five-stage framework for measuring product growth: Acquisition (users find you), Activation (first value experience / aha moment), Retention (users return), Revenue (monetisation), Referral (users invite others). Each stage has its own conversion rate; the weakest stage is the highest-leverage improvement target.
DAU / MAU
Daily Active Users and Monthly Active Users — counts of unique users who perform at least one meaningful action in a day or month. The DAU/MAU ratio (stickiness) measures how frequently monthly users return. A ratio above 0.50 indicates a highly habit-forming product.
North Star metric
A single metric that best captures the core value a product delivers to customers. All growth experiments and roadmap decisions are evaluated against it. A good North Star reflects user value (not just revenue), is hard to game in isolation, and serves as a leading indicator of long-term business health.
A/B test (experiment)
A controlled experiment that randomly assigns users to a control group (existing experience) and one or more treatment groups (new feature or change). The causal impact of the change is measured by comparing a primary metric between groups after the experiment reaches statistical significance.
Statistical significance
A result is statistically significant when the probability of observing the measured difference by chance alone (the p-value) falls below a pre-set threshold (typically p < 0.05). It does not imply practical importance — a tiny effect can be statistically significant with a large sample size.
Uplift
The percentage improvement in a metric caused by a treatment, relative to the control. For example, if the control activation rate is 20% and the treatment activation rate is 21%, the uplift is 5% (relative). Uplift is the primary output used to decide whether to ship a change.
Holdout group
A segment of users permanently excluded from a set of experiments over a longer period (weeks or months). Used to measure the cumulative, long-term impact of multiple shipped changes compared to the product as it was at the holdout's creation date — distinct from a per-experiment control group.
Conversion funnel
A sequence of steps users must complete to reach a desired outcome (e.g., sign up → verify email → complete profile → first action → paid upgrade). Funnel analysis measures the conversion rate at each step, revealing drop-off points that are the highest-priority improvement opportunities.
Growth loop
A self-reinforcing cycle where user actions generate new users or deeper engagement: viral loops (users invite users), content loops (user-generated content attracts organic search traffic), and product-led growth loops (individual users bring in their teams). Loops compound over time; traditional marketing funnels are linear and do not.
Viral coefficient (K)
The average number of new users generated by each existing user. K = (invitations sent per user) × (acceptance rate). K > 1 means the product grows exponentially without additional paid acquisition. Cycle time — how long one loop iteration takes — determines the speed of compounding growth.