Thanks, no we do not have age as the time variable, age at baseline is included as a covariate. I've been asked to analyse time to second event and the request has been for me to perform a cox regression. I have been hesitant to do so because I have concern about how age influences the outcome, however I have been asked to demonstrate how the model is inadequate. Given the large sample I am finding it difficult to establish that there is a large enough violation to justify not performing the regression. For example the log-log plots are parallel however show some very minor crossing at the start and end of the period - my boss felt it wasn't a large enough violation however I am a little more pedantic about these things. So I am trying to establish whether the hazard rate (shown above) is also a good indication of violation of assumptions. Var1= binary race variable Var2 = binary variable indicating prior exposure to a different program event2censored = 1 if censored 0 if not censored proc phreg data = derived.analysis     plots=(survival);     class var1 var2;     model timetoevent2*Event2censored(1) = baselineage var1 var2/ rl;      where baselineage < 16;     run; ... View more