This interview question evaluates metric design, causal reasoning, experiment setup, diagnostics, SQL/statistical checks, and recommendations in a realistic interview setting. A strong answer for Determine User Need for In-App Video Call Feature states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
##### Scenario
Company is considering launching a new in-app Video Call feature and has full historical user and call data available.
##### Question
Using the available data, how would you determine whether users need an in-app Video Call feature? 2. After launch, what success and guard-rail metrics would you track to evaluate feature quality? 3. Describe step-by-step how you would design and run an A/B test for this feature. 4. What are the engineering pros and cons of enforcing a hard hang-off (automatic call termination) policy, and how might that affect experiment results?
##### Hints
Think funnel, engagement, retention, power-user segmentation, experiment unit, sample size, run duration, and potential user experience trade-offs.
Quick Answer: This interview question evaluates metric design, causal reasoning, experiment setup, diagnostics, SQL/statistical checks, and recommendations in a realistic interview setting. A strong answer for Determine User Need for In-App Video Call Feature states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
A consumer messaging app is considering launching an in-app Video Call feature. You have access to full historical user and call data (e.g., messaging, audio call usage, device/network attributes, and user engagement/retention).
Questions
Using the available data, how would you determine whether users need an in-app Video Call feature before launch?
After launch, what success metrics and guard-rail metrics would you track to evaluate feature quality?
Describe step-by-step how you would design and run an A/B test for this feature.
What are the engineering pros and cons of enforcing a hard hang-off (automatic call termination) policy, and how might that affect experiment results?
Hint: Think funnel, engagement, retention, power-user segmentation, experiment unit, sample size, run duration, and potential user experience trade-offs.
Constraints & Assumptions
Preserve the scope, facts, inputs, and requested outputs from the prompt above.
If the prompt leaves a detail unspecified, state a reasonable assumption before relying on it.
Keep the answer interview-ready: concise enough to present, but concrete enough to implement or evaluate.
Clarifying Questions to Ask Guidance
Clarify the business objective, unit of analysis, time window, exposure definition, and primary metric.
State assumptions about instrumentation, randomization, sample size, and data quality.
Separate descriptive analysis from causal claims.
What a Strong Answer Covers Guidance
A metric framework with primary, guardrail, and diagnostic metrics.
A credible analysis or experiment design with clear assumptions and bias checks.
SQL/statistical logic for segmentation, variance, confidence, and data validation where relevant.
An actionable recommendation that explains trade-offs and next steps.
Follow-up Questions Guidance
What sanity checks would you run before trusting the result?
How would you handle novelty effects, seasonality, or selection bias?