When effects parameterization is used in PROC LOGISTIC, the p-values in the Odds Ratio Estimates table produced by the ORPVALUE and CLODDS= options in the MODEL statement are incorrect. The displayed point estimates and confidence limits are correct. Effects parameterization is the default parameterization method for CLASS variables and is used if the PARAM= option is not specified, or when PARAM=EFFECT is specified in the CLASS statement.

To avoid the problem, use a different parameterization such as PARAM=REF or PARAM=GLM. Alternatively, use the method described and illustrated in SAS Note 53376: "Computing p-values for odds ratios."

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