Easy interview questions in Growth & Experimentation
What counter metrics track health of weekly active users?
Tests whether you can spot growth-at-all-costs blind spots. A strong answer pairs WAU with 7-day retention, sessions per user, and error rate, mapping each to churn, shallow engagement, or bugginess.
How do you instrument a marketing funnel versus a product-led growth loop?
This tests if you distinguish linear attribution from compounding systems. A strong answer contrasts stage-tracking and CAC with viral-coefficient instrumentation, cycle-time velocity, plus identity resolution.
What fields belong in an experiment tracking event?
Tests disciplined schema thinking over random fields. Strong answers cite a tracking plan with event and user properties, environment separation, and consistency. Red flag: dumping data without a schema or single source of truth.
How do you attribute signups to Facebook, Google, and blog campaigns?
This tests URL-based campaign attribution and session persistence. A strong answer covers UTM tags, landing page parsing, cookie storage, and writing the source to the user record at signup.
Instrument a first-full-song activation event
Define 'full song' server-side, emit a typed event with user, song, and context, dedupe the first-time flag.
How do you track events and calculate funnel drop-off?
Tests event mapping and funnel math. Answer: one event per step (page view, email submit, profile done); compute relative step conversion and overall rate from top; deduplicate users. Red flag: raw pageviews instead of uniques.
How would you track a 'Sign Up' button click end-to-end?
It tests your ability to instrument a custom event and validate the pipeline. Attach a gtag listener to the button, fire a sign_up_click event, then confirm the hit in GA4 DebugView or real-time reports.
What is a conversion funnel? Instrument a three-step onboarding funnel with events.
This tests translating business funnels into concrete event instrumentation. A strong answer outlines three ordered steps, names exact events like user_signed_up and project_created, and notes unique-user counting.
How would you implement a timezone-safe, tamper-proof offer countdown?
Tests distrust of the client and server-side UTC enforcement. Outline: server owns canonical end time; client syncs clock offset to render remaining time; checkout re-validates expiry. Red flag: using local Date.now or localStorage.
How would you design a near real-time social proof notification system?
This tests low-latency event pipeline design with bounded load. A strong answer uses a fire-and-forget beacon, stream processor, and cache with TTL; it favors approximate counts and windowed aggregation.
Which three data sources would you analyze to improve activation?
This tests whether you ground hypotheses in diverse evidence before experimenting. A strong answer names qualitative feedback, funnel metrics, and behavioral analytics as distinct inputs.
What framework decides between low-effort/low-impact and high-effort/high-impact experiments?
This tests structured experiment sequencing beyond gut instinct. A strong answer picks ICE, RICE, or PIE; scores both experiments by impact, confidence, and effort or reach; then weighs opportunity cost and bandwidth.
How do you set up a button color A/B test?
Tests whether you can define a valid experiment, not just a color change. A strong answer covers hypothesis, randomization, primary metric, sample size, and significance threshold.
What is a p-value in A/B tests and what does threshold mean?
P-value is the chance of this or more extreme result if the null is true; the 5% threshold is the accepted false-positive rate.
How would you instrument a 4-step onboarding wizard?
Track Step Started and Step Completed with step_index and flow_variant; tie via distinct_id.
How do you determine if a user is 'new' for a setup guide?
This tests whether you separate account age from user state for onboarding. Good answers compare created_at (brittle) with a persistent flag (idempotent) and consider milestones. A red flag is using a timestamp as a permanent new proxy without managing reruns.
Describe the end-to-end data flow for tracking a 'Share' button click
Payload carries event type, user ID, timestamp, device, content; client batches with retry; backend validates and lands in a partitioned store.
Describe the data model and backend logic for a daily login bonus.
This tests streak state machines and calendar edge cases. A strong answer stores last_login_utc and streak_count, uses UTC day buckets, resolves timezones per user tz, and needs no leap-year logic.
What schema changes are needed to add a Pro subscription tier?
This tests normalization of billing data versus hardcoding tiers. Add a plans table with integer cents pricing, link subscriptions via plan_id, and leave users untouched. Red flag: adding a tier string column to users or storing prices in subscriptions.
Model a 3-month 20% promo discount and apply it at billing
This tests separating coupon rules from per-user redemptions. Good answers use a coupons table for the 20%/3-month rule, a redemptions table for usage, and apply the discount to the first three invoices. A red flag is hard-coding the discount on the user row.
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