Good morning
I need your help to understand the difference of running Proc MIXED in SAS 9.3 & SAS 9.4.
The same program (same dataset) running smoothly on SAS 9.3 when I run it on SAS 9.4 returns the 'WARNING: Stopped because of infinite likelihood.'.
In the data there are no repeated values.
ods output lsmeans=STAT00;
proc mixed data = rawda MAXFUNC=5000;
by paramcd param;
class usubjid studyid avisitn basecn ;
model chg = studyid avisitn basecn avisitn*basecn /solution;
repeated avisitn / subject = usubjid(studyid) ;
lsmeans basecn*avisitn ;
PARMS / NOITER ;
run;
ods output close;
Please help me to understand what did change.
Many thanks in advance
@alexal Many thanks for your promptly reply!
The program runs smoothly with your option (it works with 1e-11 too).
When I run the program in SAS 9.3 & 9.4 with the same singluar=1e-8 I do expect the Least Squares Means being identical for both versions. This is not the case. I get the same Estimate, DF & Pr > |t|, but Standard Error & T values are different. Which is the reason?
Many thanks for helping me!
You are welcome!
You can find the information on the SINGULAR= option in the PROC MIXED documentation here.
SINGULAR=number
tunes the sensitivity in sweeping. If a diagonal pivot element is less than D*number as PROC MIXED sweeps a matrix, the associated column is declared to be linearly dependent upon previous columns, and the associated parameter is set to 0. The value D is the original diagonal element of the matrix. The default is 1E4 times the machine epsilon; this product is approximately 1E–12 on most computers.
In your case, the default criterion might be too stringent. That is why I suggested the singular=1e-8 option.
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