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Investigate why an advertiser’s spend decreased

MetaData Scientist · Technical Screen
EasyData ScientistTechnical ScreenAnalytics & Experimentation

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This question tests your ability to systematically isolate the root cause of a drop in advertising spend by decomposing metrics and evaluating external versus internal factors.

Scenario

You are a Data Scientist supporting the Video Ads team. An advertiser reports that their total spend on the platform dropped by 25% week-over-week (WoW). They are concerned that their ads are underperforming or that there is a technical issue with the bidding infrastructure.

Task

How would you structure a diagnostic investigation to determine why this advertiser's spend decreased? Provide a step-by-step framework to isolate the cause.

Considerations

  • Decomposition: Spend is a product of several underlying metrics. How can you break this down?
  • Internal vs. External: How do you differentiate between issues related to the advertiser’s settings versus market-wide phenomena?
  • Data Sources: What specific dimensions or metadata would you examine in your logs?

Expected Output

  • Outline a logical framework (e.g., top-down approach).
  • Identify the key metrics you would query (e.g., Impressions, CPM, Bid win rate, Auction volume).
  • Explain how you would rule out a system-side bug versus an advertiser-side strategy change.

Hints

Hint 1

Start by decomposing 'Spend' into its mathematical components, such as Impressions multiplied by Average Cost Per Mille (CPM).

Hint 2

Compare the advertiser's performance metrics against a control group or industry benchmarks to see if the decline is specific to this client or a systemic marketplace trend.

Hint 3

Investigate changes in the advertiser's own account settings, such as budget caps, bid strategies, or creative expiration dates.

Follow-up questions

  • If you found that the 'Bid Win Rate' dropped significantly, what potential technical or market factors would you investigate next?
  • How would you determine if the drop in spend was caused by a reduction in inventory availability for the specific target audience?
  • If the spend decrease coincided with a new ad policy rollout, how would you quantify the impact of that policy change on this advertiser specifically?