In PROC MIANALYZE, the COVB= data set is only needed when you specify the MULT option in either the PROC MIANALYZE statement or in the TEST statement. Otherwise, it is recommended that you remove the COVB= option.

If you specify the COVB= and MULT options and receive an error message that either a variable is not found or that your covariance matrix is not symmetric, the most common cause for this is that the EFFECTVAR= suboption of the COVB= option has not been properly assigned. See the table below for a listing of each of the EFFECTVAR= values and the corresponding procedures.

EFFECTVAR=	Valid Procedures
STACKING	GENMOD LIFEREG LOGISTIC PHREG PROBIT QUANTREG ROBUSTREG SURVEYLOGISTIC
ROWCOL	GLIMMIX MIXED