Hi Rajesh, Thank you for your fast reply! Very kind of you, thank you very much for helping me. So I tried to do it and it works for few, but I got errors in others. I put it like this: proc genmod data=C descending order=data; class group cow dl po; model react=group dl po/ d=bin link=logit; repeated subject=cow/ type=cs; estimate "group" group1 -1 / exp; estimate "dl" dl1 -1/ exp; run; group is control and treat dl is the day of lactation (1, 3, 5, 7, 9, 11, 13, 15, 17 and 19) po is parturition order react is the reactivity scored as 0 (without reactivity) and 1 (with reactivity). In my table, I will just compare the score 1 (with reactivity). As example below: DL Reactivity Group Treated Group Control P value 01 50 80 03 30 65 05 20 35 I would like to have the P value. Sometimes the difference between groups is large and the P value isn't significative. And sometimes have errors like this: NOTE: PROC GENMOD is modeling the probability that react='1'. WARNING: The negative of the Hessian is not positive definite. The convergence is questionable. WARNING: The procedure is continuing but the validity of the model fit is questionable. WARNING: The specified model did not converge. WARNING: Negative of Hessian not positive definite. WARNING: The generalized Hessian matrix is not positive definite. Iteration will be terminated. ERROR: Error in parameter estimate covariance computation. ERROR: Error in estimation routine. I'm bit new in this... and a desesperate student. Please, if you can help me, I am really glad. Thank you again. Aska.
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