I am having some trouble understanding the output from proc mixed (as
opposed to Proc ttest)  How is it that the P values associated with F
tests in SAS proc mixed are two-tailed when the F test done in MIXED
or GLM appears to be one-tailed?
Perhaps I have misunderstood what happens.  If so, please clarify:
Is the F test in proc mixed one-tailed?
Is the associated P value two-tailed?
If so, please explain why it works that way...
If not, please advise on SAS code that would produce two-tailed
values.