The Power and Sample Size Application

Survival functions can be specified as median survival times, hazards, or a combination of hazards for one group and hazard ratios. These all assume exponential curves.

Suppose you are interested in comparing the proposed and existing treatments using their median survival times. The survival times are five years and four years for the two groups, respectively.

Click the Survival Functions tab and examine the list of alternate forms available in the Select a form: list. For this example, select the Group median survival times option.

For the example, enter 5 and 4 in the first row of the table. The completed table is shown in Figure 78.90.

You can enter one or more sets of two median survival times. The results of the analysis are not shown.