Simpson's Paradox
Probability & Statistics
About Simpson's Paradox
Compare within-group and pooled success rates, reveal aggregation reversals, and test a common population mix.
Simpson's paradox describes an association that changes when observations are combined or separated into groups. In the strict reversal explored here, option A has a higher success rate than option B in each of two groups, yet B has the higher overall rate. The arithmetic is consistent: the options can have different proportions of observations in the two groups. This original fictional example isolates that mechanism without making a claim about any real treatment, population or experiment.
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