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.
Describe RICE scoring and architect data pipelines for Reach and Effort
Define RICE; automate Reach via event streams with time windows; automate Effort from PM tool estimates with calibration.
How do you design allocation logic to minimize concurrent A/B test interactions?
Compare mutual exclusion with layered randomization via layers and reservations; stress isolation vs throughput.
How would you structure an event schema for funnel and cohort analysis?
This tests analytical event modeling. Use an immutable log with one row per event; attach context user_id, session_id, campaign; use a wide atomic table plus extensible contexts for funnel and cohort queries without joins.
How would you architect long-term holdback experiment groups?
Tests longitudinal causal inference and engineering tradeoffs for multi-month isolation. A strong answer covers bucketing, delayed metrics, and cross-experiment guards. Red flag: daily re-randomization or ignoring survivorship bias in aging cohorts.
Architect an experimentation dashboard for culture
Searchable experiment repository, structured hypotheses, results regardless of outcome, and cross-team discovery.
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.
Describe the SQL and data model for weekly cohort retention
Join users and activity, compute week offset per user, group by cohort and offset for retention.
Propose a strategy to enforce a consistent analytics event schema
Schema registry with CI validation, typed SDK wrappers blocking bad builds, plus ingestion-time rejection.
How do you instrument client and server to debug payment drop-offs?
Tests designing telemetry that distinguishes intent from errors across the stack. Strong answers use visibility pings for abandonment, validation events for client errors, and gateway status codes for backend failures.
Describe the architecture for multi-touch attribution with time-decay
Stitch IDs, stream events to warehouse, sessionize journeys, then apply decay weights in SQL.
How do you architect a global notification holdback group?
Tests persistent control-group isolation without breaking critical flows. Strong answers use deterministic sticky bucketing by user ID, separate marketing and transactional namespaces, and audit holdout bleed.
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.
What causes client order_completed events to diverge from backend records?
Tests end-to-end event reliability. Separate client failures (network, ad blockers, duplicates) from backend gaps (idempotency, validation, races) and propose timestamped join analysis. Red flag: blaming users or fixing before measuring gap direction.
Explain user identity stitching across devices and SDK roles
Tests event-level identity resolution. A strong answer covers anonymousId per device, the identify call binding anonymous events to userId, and backend merge handling out-of-order events. Red flag: claiming cookies alone stitch mobile and web.
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