Simpson's Paradox
Simpson's Paradox
Seven examples of Simpson's paradox are presented. The pooled data is generally misleading, as certain important variables are ignored. When the data is conditioned on the additional variable (e.g. the race of the victim in Florida murder cases, or the age of the smoker or nonsmoker), the results are the opposite of what one sees in the pooled data. The models shown give a logistic regression summary of the effect of certain parameters on the response variable, which is always taken to be the "good" thing: survival, not getting the death penalty, hits, or weight loss. The color is preserved in the two plots; that is, third class on the Titanic is red both in the pooled and conditioned plots. The case of employment data is interesting, as there the pooled data is a more reliable indicator of economic health than the separated data.