For almost twenty years, I have been trying to convince the scientific community that the confusion over Simpson’s paradox is a result of incorrect application of causal principles to statistical proportions. If we use causal notation and diagrams, we can clearly and unambiguously decide whether Drug D prevents or causes heart attacks. Fundamentally, Simpson’s paradox is a puzzle about confounding and can thus be resolved by the same methods we used to resolve that mystery. Curiously, three of the four 2016 papers that I mentioned continue to resist this solution.
