"So I should conclude that all GROUP variables must be placed before the ORDER variable in the column statement. Else the vertical merge will not work."
Yes. I think so.
"And there can only be one ORDER variable in a report?"
No. I don't think so. You can take ORDER the same as GROUP. If you replace all the GROUP with ORDER in the code, you will find
that still worked.
PROC REPORT take variables from left to right. So when it meet ORDER variable(order) ,will take it as a GROUP usage variable,
Therefore when variable pvalue after order, PROC REPORT will take ORDER as the first group variable and PVALUE as the second group variable. That is wrong. So you need put PVALUE before ORDER.
... View more