An example that is frequently cited in elementary statistics courses for the unreliability of survey data, is that when people are surveyed about their sexual history, men report more lifetime female partners on average than women report male partners. (A high-quality example is this UK survey from 1992, where men reported 9.9 female partners on average, while women averaged 3.4 male partners. It’s possible to tinker around the edges with effects of changes over time, and age differences between men and women in sexual relationships, but the contradiction is really inescapable. One thing that is quite striking in this survey is the difference between the cross-sectional and longitudinal pictures, which I’ve discussed before. For example, men’s lifetime numbers of sexual partners increase with age — as they must, longitudinally — but among the women the smallest average number of lifetime sex partners is in the oldest group.)
In any case, I was reminded of this when reading Stephen Greenblatt’s popular book on the rediscovery of De rerum naturae in the early 15th century by the apostolic secretary Poggio Bracciolini, and the return of Epicurean philosophy more generally into European thought. He cites a story from Poggio’s Liber Facetiarum a sort of jokebook based on his experiences in the papal court, about
dumb priests, who baffled by the fact that nearly all the women in confession say that they have been faithful in matrimony, and nearly all the men confess to extramarital affairs, cannot for the life of them figure out who the women are with whom the men have sinned.