The New York Times reported results of a study on the effects of AZT in slowing the development of AIDS symptoms (February 15, 1991). Veterans whose immune symptoms were beginning to falter after infection with HIV were randomly assigned to receive AZT immediately or wait until their T cells showed severe immune weakness. During the 3-year study, of those who received AZT, 11 of 63 black subjects and 14 of 107 white subjects developed AIDS symptoms. Of those who did not receive AZT, 12 of 55 black subjects and 32 of 113 white subjects developed AIDS symptoms. Use model building, including checking fit and interpreting effects and inference, to analyze these data.