Graphics Reference
In-Depth Information
Figure 13-30. Splitting Dept vertically, Gender horizontally, and Admit horizontally
The example here illustrates a classic case of Simpson's paradox, in which a relationship
between variables within subgroups can change (or reverse!) when the groups are combined. The
UCBerkeley
table contains admissions data from the University of California-Berkeley in 1973.
Overall, men were admitted at a higher rate than women, and because of this, the university was
sued for gender bias. But when each department was examined separately, it was found that they
each had approximately equal admission rates for men and women. The difference in overall ad-
