Concept · Cognitive Bias: Causal and statistical fallacies
Simpson's paradox
Origin: Simpson, 1951; Yule, 1903
Biological Parallel
A treatment improves survival in both males and females when analyzed separately—yet decreases survival overall. Simpson's paradox appears when subgroup proportions differ. In evolutionary biology: a trait may be advantageous in every local environment yet disadvantageous across the metapopulation due to migration patterns. Aggregation masks causation. What holds for parts doesn't necessarily hold for the whole when composition varies.