All simulators
Simpson's Paradox Lab
Change who gets which treatment and watch the pooled comparison reverse the stratified one.
Day 15: Phase 1 Capstone: Simpson's Paradox, Conditional Independence & Selection BiasTreatment A success rateTreatment B success rate
⚠️ Simpson's paradox: A is better in both strata, but the pooled comparison favours B, because the arms treat different case mixes.
Defaults are the kidney-stone study (Charig et al., 1986). The pooled comparison uses each arm's own case mix; the standardised one uses the same case mix for both arms.