*-- SAS 9.3 ---; %include catdata(cowles); data cowles; set cowles; format Sex sex. Volunteer volun.; proc print data=cowles(obs=20); run; *-- interaction model, with effect plots; proc logistic data=cowles outest=parm descending ; class Sex; model Volunteer = Sex Extraver | Neurot / lackfit ; effectplot slicefit(x=Extraver sliceby=Neurot) / at(sex=1.5) noobs; effectplot slicefit(x=Neurot sliceby=Extraver) / at(sex=1.5) noobs; effectplot contour(x=Neurot y=Extraver) / at(sex=1.5) noobs; run;