@kli15 wrote: I see, thank you so much for the explanation! First time using findc and I have been so confused! You aren't the first and won't be the last. I seem to remember similar confusion a few times in the past. And SAS was something like the 7th programming language (plus 5 or 6 dialects of Basic) I learned. ... View more

Hello Than, I have two suggestions: 1) I think the only reason for why it sometimes Works and sometimes not is the random samples in the assessment. If you dont need to assess the functional form, then you shold omit the assessment statement, and the error will most likely disappear. 2) Also, since preedin is not timedependent, you should calculate logpreedin in a dataset before you run PHREG. Then, phreg will see logpreedin as any other fixed covariates, and the log-transformation will not be used in the assessment neithter (becase logpreedin is then already a transformed variable). Therefore, defining the logpredin in a dataset should also remove the error. Good luck. Jacob ... View more