Dear All, We are carrying out a study in which patients are followed-up during a year with quarterly visits. In each visit they are teste for many diseases. One of them is hepatitis B. We are running a logistic model to measure the difference in proportions of participants with hepatitis B (HEPAT_B) in week 0 and week 52. As the measures are from the same individuals, we used a conditional logistic. Generally, I use proc genmod with the identification of individuals (copid). PROC GENMOD DESCENDING; CLASS COPID Week (REF='0'); MODEL HEPAT_B=week/ DIST=BIN LINK=LOGIT; REPEATED SUBJECT=COPID/TYPE=UN; ESTIMATE 'TEMPO' week 1 -1/EXP; RUN; It runs perfectly. But because there in no event at week 52, I tried to include some exact test. I used the following command: PROC LOGISTIC DATA=TOTAL exactonly; CLASS week; STRATA COPID; MODEL HEPAT_B=week; EXACT week; RUN; It did not work. However, if I used only the exact logistic without the option strata, the model works fine. proc logistic data=TOTAL; class week/ param=ref; model HEPAT_B=week; exact week; run; I would like to know how to can I used a conditional logistic model with a option exact. Thank you in advance. Regards, Iuri SAS Output: NOTE: ODS Graphics are not available when the EXACTONLY option is specified. WARNING: There are no valid observations since all strata are noninformative. NOTE: The SAS System stopped processing this step because of errors. NOTE: There were 4473 observations read from the data set WORK.TOTAL. NOTE: PROCEDURE LOGISTIC used (Total process time): real time 0.04 seconds cpu time 0.01 seconds
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