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Data Driven Analysis and Optimization Questions

Using data to diagnose problems, prioritize experiments, and drive optimizations. Includes clarifying metrics and goals, identifying and gathering relevant data, analyzing trends and anomalies, forming testable hypotheses, designing experiments such as A B tests, interpreting statistical significance, distinguishing correlation from causation, and recommending actions based on insights. Interviewers look for structured analytic workflows, comfort with basic statistics, and the ability to translate analysis into measurable product or operational improvements.

HardTechnical
40 practiced
Design a testing strategy to validate an offline experiment analysis pipeline (that consumes nightly event aggregates and computes treatment effects). Include unit tests, end-to-end tests, synthetic datasets to validate power/coverage, and how you'd test for edge cases like missing cohorts and heavy-tailed revenue distributions.
MediumTechnical
35 practiced
A product manager asks you to implement a metric pipeline for 'time to first purchase' (days between signup and first purchase) aggregated weekly. Describe the ETL steps, the canonical tables you would create in the warehouse (with schemas), how you would handle users with no purchases, and how you would keep the metric backfillable when schema or logic changes.
HardTechnical
38 practiced
Given an A/B test where the primary metric is 'purchase rate' (binary per user within the test window), describe how to compute the required sample size to achieve 80% power to detect a 2% absolute lift from a baseline 10% purchase rate at alpha=0.05. Describe inputs, formulas (briefly), and how you'd implement a power calculation script in Python for multiple variants.
EasyTechnical
57 practiced
Create an example JSON schema for an experiment telemetry event that captures assignment information and exposure metadata necessary for accurate analysis. Include fields for experiment_id, variant_id, user_id, device_id, cohort, exposure_time, request_id, and context. Explain why each field is important and which are required vs optional.
EasyTechnical
34 practiced
Explain the difference between correlation and causation. Provide three real-world examples where correlation might mislead product decisions and describe how a Data Engineer can help enable stronger causal inference (data collection, instrumentation, and experiment support).

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