Hall-Wellner Confidence Bands and Homogeneity Test

You can use the following statements to add Hall-Wellner confidence bands (Hall and Wellner, 1980) to Figure 23.1 and display the p-value from a test that the strata are homogeneous:

proc lifetest data=sashelp.BMT plots=survival(cb=hw test);
   time T * Status(0);
   strata Group;

The results are displayed in Figure 23.4. The Hall-Wellner confidence bands extend to the last event times. The small p-value supports rejecting the hypothesis that the groups are homogeneous.

Figure 23.4: Confidence Bands and Homogeneity Test