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Meta·Data Scientist·Technical Phone Screen·Senior

Senior
May 2026

Summary

Meta DS interview with a product analytics case focused on their video ads business. One meaty question that spiraled into a bunch of sub-parts about spend drops, root cause isolation, and experiment design. Felt like a real on-the-job scenario more than a textbook problem.

Questions Asked (1)

Q1

An advertiser reports that their Brand Ads spend has dropped significantly over the past two weeks. How would you figure out whether the drop is real, whether it's isolated to this advertiser or a broader issue, identify the root cause, and recommend follow-up analyses or experiments?

Root Cause AnalysisProduct Analytics & MetricsA/B Testing & Experimentation
Author's notes

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AI HintsAI Generated

Suggested Approach

Start by validating the data and defining the metric precisely, then segment the drop by dimensions like time, geography, and device to check if it's isolated. Compare against benchmarks and other advertisers to determine if it's a broader issue, then use root cause analysis techniques like funnel breakdown and correlation with external factors. Finally, propose follow-up analyses and experiments to confirm the cause and recommend actions.

Pro tip: Always validate the data first—check for tracking issues, logging errors, or changes in attribution that could create a false drop. Also, consider seasonality and external events (e.g., holidays, competitor activity) before diving deep.

1. Validate the data and define the metric

Ensure the drop is real by checking data pipelines, tracking, and metric definitions. Confirm the exact metric (e.g., spend, impressions, clicks) and time period.

2. Segment and compare

Break down the drop by dimensions (time, geo, device, campaign, audience) to see if it's isolated to specific segments. Compare with other advertisers and overall platform trends to determine if it's advertiser-specific or systemic.

3. Identify root cause

Analyze potential causes: internal (budget changes, targeting, creative fatigue) and external (competition, seasonality, platform changes). Use funnel analysis to pinpoint where the drop occurs (e.g., impressions, clicks, conversions).

4. Recommend follow-up analyses and experiments

Propose A/B tests or holdout experiments to test hypotheses (e.g., creative refresh, bid strategy change). Suggest deeper analyses like cohort analysis or attribution modeling to understand long-term impact.

Key Points to Mention

  • Data validation: check for tracking errors, logging issues, or attribution changes.
  • Segmentation: analyze by time, geography, device, campaign, audience to isolate the drop.
  • Benchmarking: compare with other advertisers and platform-wide trends to assess scope.
  • Root cause analysis: consider internal factors (budget, targeting, creative) and external factors (seasonality, competition, platform changes).
  • Funnel analysis: break down the ad delivery funnel to identify where the drop occurs.
  • Experimentation: design A/B tests or holdout experiments to confirm hypotheses and measure impact.

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