Hi,   I would need help to understand how the pvalue is computed when using UPPER option in a PROC MIXED. Here is my mixed procedure: PROC MIXED data=dummyall plots=residualpanel method=reml;      CLASS   diet timec id timeplan;      MODEL pulse= diet timec diet*timec pulsebase/ ddfm=kr;      REPEATED timec / type=sp(pow)(timeplan) subject=id;      LSMEANS diet*timec/diff=all cl;      LSMESTIMATE diet*timec 'Change at Timec=2 - Diet 1 vs diet 2'  1 0 0 -1 0 0 / upper alpha=0.05 cl ; RUN;   I have the impression the pvalue of the one sided test is 0.5*(pvalue two tailed) in case the pvalue is significant and the pvalue of the one sided test is 1-0.5*(pvalue two tailed) in case the pvalue is not significant. Though I thought the pvalue calculation was based on which alternative hypothesis is considered (diff>0 or diff<0). Why does the way the pvalue is computed change according to the results? Can anyone help me to understand?   Thanks! ... View more