Given simple random samples X1 , . . . , Xn and Y1 , . . . , Ym from two infinite populations, one often wishes to test for a dif- ference between the two populations. Such tests can be done either in parametric fashion, as with the familiar two-sample t test, or in nonparametric fashion. One commonly used nonparametric test is the two-sample Kolmogorov–Smirnov test.