Overview (TIME PROGRAM command)
TIME PROGRAM
is required
to define time-dependent covariates. These are covariates whose values change
during the course of the study.
Basic Specification
The basic
specification is the TIME PROGRAM
command
followed by one or more commands that define time-dependent covariates.
Syntax Rules
-
TIME PROGRAM
and the transformations that define the time-dependent covariate(s) must precede the command that analyzes the time-dependent covariate(s). - A time-dependent covariate is a function of the current time, which is represented by the special variable T_.
- The active dataset must not have a variable named T_. If it does, rename the variable. Otherwise, you will trigger an error.
- T_ cannot be specified as a covariate. Any other variable
in the
TIME PROGRAM
can be specified on the covariate list. - For every time-dependent covariate,
values are generated for each valid case for all uncensored times in the same
stratum that occur before the observed time. If no
STRATA
subcommand is specified, all cases are considered to belong to one stratum. - If any function defined by the time program results in a missing value for a case that has no missing values for any other variable used in the procedure, this causes an error.