The default EFFECTPLOT, as noted earlier, gives a visual assessment of the variable effects and interaction via a surface plot. You can also use the Margins macro to estimate the slope (instantaneous rate of change) of the response surface at specified points. For example, the following statements produce the surface plot and estimate slopes at points on the surface for the continuous variables in the neuralgia data in the example titled "Logistic Modeling with Categorical Predictors" in the PROC LOGISTIC documentation. The variable PAINNUM is a 0,1 coded numeric version of the character Pain variable in that data set. The macro requires a numeric response. See also this note for more on assessing the effect of continuous variables in a model.
proc surveylogistic data=neuralgia;
model Pain=Age|Duration;
store log;
run;
proc plm restore=log;
effectplot;
run;
data atdat;
do duration=20,40;
do age=60 to 80 by 5;
output; end; end;
run;
%margins(data=neuralgia, response=painnum, roptions=event='1',
model=age|duration, dist=binomial,
effect=age, at=duration age, atdata=atdat, options=cl)
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