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Detect and address Simpson’s paradox

MetaData Scientist · Onsite

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This question evaluates understanding of aggregation bias and Simpson's paradox, proficiency with stratified or mixed-model estimators, heterogeneity testing, and experiment decisioning within Analytics & Experimentation for a Data Scientist role.

An experiment shows +1.2pp overall conversion uplift, yet the segment‑level effects are −0.5pp (New) and +2.0pp (Returning). a) Construct a concrete example showing how a shift in segment mix can create Simpson’s paradox. b) Pre‑register a stratified estimator (or MMRM) that protects against aggregation bias. c) Specify an interaction test for heterogeneity and a decision rule when heterogeneity is material (e.g., segment‑specific rollout vs. global ship).