Simpson's Paradox: An Anatomy
Judea Pearl · eScholarship (California Digital Library) · 2011
This report discusses the reversal eect known as Simpson's paradox from a causaltheoretic viewpoint.It analyzes the reasons why the eect has been (and still is) considered paradoxical and why its resolution has been so late in coming.The report is extracted from a forthcoming book Causality [Pearl, 2000], and assumes some familiarity with causal diagrams and the do() ( o r set()) notation (e.g., [Pearl, 1995]).