It appears SAS FREQ computes the odds ratio solely as the usual OR=(ad)/(bc) method. It does not provide the "exact" OR maximum likelihood estimate which is from Fisher's non-central hypergeometric distribution. These are not the same. It does appear as though SAS will estimate the "exact" confidence limits using Fisher's non-central hypergeometric distribution, but for some reason does not provide the MLE for the OR. The pmf from Fisher's non-central hypergeometric distribution can be considered a likelihood with the OR as the parameter. This is what the fisher.test() function uses in R. Can SAS add this to SAS/STAT or make it clear how to extract the "exact" OR if this approach already exists?
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