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This question evaluates a data scientist's competency in time-series data manipulation and metric validation, focusing on calculating Year-over-Year advertising revenue with SQL/Python and window functions while recognizing pitfalls associated with rolling sums.

  • Medium
  • Meta
  • Data Manipulation (SQL/Python)
  • Data Scientist

Improve YoY Revenue Analysis with Complementary Metrics

Company: Meta

Role: Data Scientist

Category: Data Manipulation (SQL/Python)

Difficulty: Medium

Interview Round: Onsite

ads_revenue +------------+-----------+ | date | revenue | +------------+-----------+ | 2023-01-01 | 120000 | | 2023-02-01 | 125500 | | 2024-01-01 | 140000 | | 2024-02-01 | 145000 | | 2024-03-01 | 150000 | +------------+-----------+ ##### Scenario Analyzing advertising revenue performance ##### Question Write SQL to calculate Year-over-Year (YoY) ads revenue by month. What potential pitfalls exist when using a rolling sum in this context? Suggest ways to improve or complement the YoY growth-rate metric. ##### Hints Think window functions, seasonality, data sparsity, normalization.

Quick Answer: This question evaluates a data scientist's competency in time-series data manipulation and metric validation, focusing on calculating Year-over-Year advertising revenue with SQL/Python and window functions while recognizing pitfalls associated with rolling sums.

Last updated: Mar 29, 2026

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