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Meta·Software Engineer·Technical Phone Screen·Senior

Senior
Apr 2026

Summary

Got a classic product analytics case for a data science role at Meta. Just the one question but they clearly wanted to see a structured diagnostic approach, not just a list of things to check.

Questions Asked (1)

Q1

You're a data scientist at Meta and Facebook's daily post views suddenly drop 10%. How do you investigate?

Root Cause AnalysisProduct Analytics & Metrics
Author's notes

I started with data integrity because I've been burned before by jumping to product explanations when it was actually a logging bug.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the metric definition and validating the data pipeline to rule out instrumentation or logging issues. Then segment the drop by dimensions like platform, region, user cohort, and time to localize the cause, and finally correlate with recent changes or external events to identify the root cause.

Pro tip: Always check if the drop is real before diving deep—many 'metric drops' are actually data pipeline failures or logging bugs. Also, consider that a 10% drop might be intentional (e.g., due to a product change) or a shift in user behavior, so align with product and engineering teams early.

1. Clarify and Validate the Metric

Confirm the exact definition of 'daily post views' and check if the drop is real by verifying data pipelines, logging, and aggregation logic. Look for anomalies in data freshness or completeness.

2. Segment and Localize

Break down the metric by dimensions such as platform (iOS, Android, web), region, user demographics, and time of day to see if the drop is concentrated in a specific segment.

3. Correlate with Internal Changes

Check recent code deployments, A/B tests, feature launches, or infrastructure changes that could impact post views. Use dashboards and version control to identify potential culprits.

4. Consider External Factors

Evaluate if external events (e.g., holidays, competitor launches, news events) or seasonal trends could explain the drop. Compare with historical data for similar periods.

5. Form and Test Hypotheses

Based on segmentation and correlations, form hypotheses about the root cause and validate them with further analysis or experiments. Communicate findings and recommended actions.

Key Points to Mention

  • Data quality checks: ensure the drop is not due to logging errors, pipeline failures, or metric definition changes.
  • Segmentation: analyze by platform, region, user cohort, and time to isolate the affected population.
  • Recent changes: review deployments, A/B tests, and feature flags that might impact post views.
  • External factors: consider seasonality, holidays, or competitor actions.
  • Hypothesis testing: use statistical methods or experiments to confirm the cause.
  • Communication: collaborate with cross-functional teams and provide clear updates.

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.