I am running a logistic regression and I need odds ratios and confidence limits for interaction terms using proc logistic. I am using the contrast statement but don't know if the matrix I have specified is right. For example, I am looking at the following interactions, 1) group*age and 2) group*sex where group, age and sex are categorical variables having values 1 and 0. The formatting of the variables is as follows: Sex = 1 if Sex='Male' or Sex=0 if Sex='Female' Age = 1 if the age of a particular subject is greater than the median age or 0 otherwise. group = 1 if treatment = 'A' , group = 0 if treatment='B' Here is the SAS code: /* All variables below including scin_30day are categorical variables with values 1 and 0 EXCEPT for the variable BASE which is continuous*/ /*I need to add interaction terms group*age, group*sex, group*BMIn, group*VIsn to the model and see if they are significant and at the same time need Odds ratios and CL values in the output dataset*/ /*Do I specify the interactions in the contrast statement, if yes, how do I write the contrast statements for the interactions above??*/ PROC LOGISTIC DATA = final_dataset descending; class group agen Male racen DIABn CR2n logn stsn ECMRGn EFN Frailn scoren MMSEn BMIn VISn; MODEL scin_30day = group BASE agen Male racen DIABn CR2n logn stsn ECMRGn EFN Frailn scoren MMSEn BMIn VISn/rsquare lackfit; ods output ParameterEstimates=dPara1 OddsRatios=dOdds1; RUN;
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