You can use the following statements to add Hall-Wellner confidence bands (Hall and Wellner 1980) to FigureĀ 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;
run;
The results are displayed in FigureĀ 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 4: Confidence Bands and Homogeneity Test
