Wikimedia Foundation Data Scientist Interview Questions
The questions to prepare for a Wikimedia Foundation Data Scientist interview. Questions from real interview reports rank first. Updated daily.
Optimize a slow PostgreSQL query on a large dataset by choosing better filters, joins, and indexes.
Calculate three-day rolling user activity averages and classify behavior trends with SQL window functions.
Optimize a billion-row AWS query by reducing scanned data, pre-aggregating requests, and preserving daily performance metrics.
Amazon Web ServicesFramework for turning customer behavior data into concrete growth opportunities, with clear segmentation, unmet jobs, and prioritization.
Define a success metric for a new feature that captures real user value, not just raw usage.
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Identify major online experimentation pitfalls and explain practical mitigations for SRM, network effects, peeking, and novelty.
Outline the first checks to diagnose a sudden drop in a core product metric, starting with data quality, scope, and decomposition.
Tests prioritization, ownership, stakeholder alignment, and resource management under pressure.
Tests influence without authority when data conflicts with senior judgment, including stakeholder management and clear communication.