Problem solved. The formula I was using was not based on a scale parameter. What I needed to be using was: where x is time, u is the intercept, and s is the scale parameter. The formula I was used to using in Proc Logistic requires slightly different parameters. DATA dummydata; INPUT vid failtime ; DATALINES; 1 45 2 55 3 56 4 57 5 57 6 59 7 60 8 65 9 70 10 75 ; run; proc lifereg data=dummydata plots=probplot; model failtime= /d=logistic; output out=a cdf=pred; run; proc print data=a; title "Lifereg predicted values"; run; data dummydata2; set dummydata; predictedmortality=1/(1+exp(-(59.5050+failtime*4.4536))); run; proc print data=dummydata2; title "Incorrect Formula predicted values"; run; data dummydata3; set dummydata; predictedmortality=1/(1+exp(-((failtime-59.5050)/4.4536))); run; proc print data=dummydata3; title "Correct predicted values"; run; Ultimately I needed to report the parameter estimates with the correct formula because I have no idea what specific time others would need to know the mortality for. Otherwise I could have just had SAS spit out a single value for a time of interest, but that would have been feasible in this case.
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