Keep in mind that all observations with the same value of the SUBJECT= variable in GENMOD's REPEATED statement are considered correlated, and any two observations with different values are considered uncorrelated. Further, the event/trials syntax allows you to specify a set of independent trials. So, the two analyses are making very different assumptions about the data. With events/trials syntax, the 36 trials in the clinic 1, trt 1 set are treated as independent as are the 37 trials in the clinic 1, trt 2 set, but any two trials in differing sets are treated as correlated. However, in the analysis without events trials syntax, all 36+37 trials in clinic 1 are treated as correlated.
Also, because the working correlation in the events/trials analysis is extremely high, GENMOD is unable to converge. If you use type=fixed(1,.99,.99,1) instead of type=cs to limit the correlation, it can converge.
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