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Showing posts from January, 2011

Time-dependent variables and SAS PHREG

There are several ways to include time-dependent variables in a call to SAS' Proc PHREG: Programming statements within PHREG or data steps combined with PHREG counting process format, i.e. in the model statement we use the syntax model (t_in,t_out)*censored(0) = X1 ... Xn; instead of model t*censored(0) = X1 ... Xn; Click the title to download the following SAS macro I have written. If you find an error please report it, otherwise you are free to use it. Another macro that can be used for the purpose of splitting a data set according to time-dependent variables is the Lexis macro developed by Bendix Carstensen %LEXIS /*Macro for splitting data according to 0-1 time dependent variables*/ %macro split_time( filein, /*Data set file containing td_date among other variables*/ id, /*Patient id - needed since we sort wrt. id and datein - could be removed */ td_var, /*Created 0-1 time-dependent variable*/ td_date, /*Date for update of timedependent variable*/ datein, /*Entry date*/