A Nice Visual Presentation of Simpson's Paradox (via Vudlab @ UCBerkeley)

simpson“In 1973, the University of California-Berkeley was sued for sex discrimination. The numbers looked pretty incriminating: the graduate schools had just accepted 44% of male applicants but only 35% of female applicants. When researchers looked at the evidence, though, they uncovered something surprising:

If the data are properly pooled…there is a small but statistically significant bias in favor of women.

By “properly pooled,” the investigators at Berkeley meant “broken down by department.” Men more often applied to science departments, while women inclined towards humanities. Science departments require special technical skills but accept a large percentage of qualified applicants. In contrast, humanities departments only require a standard undergrad curriculum but have fewer slots.”