The ICLIFETEST Procedure

The following statements are available in the ICLIFETEST procedure:

At a minimum, you must provide the PROC and TIME statements, and you must specify the left and right boundaries of the intervals in the TIME statements. For instance, the following statements compute a nonparametric estimate of the survival function:

proc iclifetest;
   time (Left, Right);
run;

You use the STRATA statement to obtain separate survival estimates for different groups of the input data. The ICLIFETEST procedure produces an individual survival estimate for each group that is formed by one or more variables that you specify in the STRATA statement.

You use the TEST statement to test whether the underlying survival functions are the same between the groups. When you specify both the TEST and STRATA statements, PROC ICLIFETEST produces a stratified test in which the comparisons are conditional on the strata. The variables that you specify in the STRATA statement must be different from the variables that you specify in the TEST statement. Note that this setup is different from that of the LIFETEST procedure, in which survival comparisons are handled implicitly by the STRATA statement.

The rest of this section provides detailed syntax information for each statement, beginning with the PROC ICLIFETEST statement. The remaining statements are covered in alphabetical order.