Hi! I am comparing two models by the likelihood ratio test and follow the instruction here:https://support.sas.com/kb/24/474.html and I found a script here for the proc logisitic proc logistic data = full_model;
model dependent_var = independent_var(s);
ods output GlobalTests = GlobalTests_full;
run;
data _null_;
set GlobalTests_full;
if test = "Likelihood Ratio" then do;
call symput("ChiSq_full", ChiSq);
call symput("DF_full", DF);
end;
run;
proc logistic data = reduced_model;
model dependent_var = independent_var(s);
ods output GlobalTests = GlobalTests_reduced;
run;
data _null_;
set GlobalTests_reduced;
if test = "Likelihood Ratio" then do;
call symput("ChiSq_reduced", ChiSq);
call symput("DF_reduced", DF);
end;
run;
data LRT_result;
LR = &ChiSq_full - &ChiSq_reduced;
DF = &DF_full - &DF_reduced;
p = 1 - probchi(ChiSq,DF);
run; I just wondered how to turn this in proc surveylogistic because I find that the degree of freedom is different. I cannot get the DF by this script since in proc survey logistic, the globaltest has a denominator DF and a numerator DF. But according to the SAS document, The LRT statistic has an approximate chi-square distribution with degrees of freedom equal to the difference in the number of parameters between the full and reduced models. Besides, the numerator DF was corrected by the Rao-Scott test in proc surveylogistic and is different from the difference in the number of parameters. Which DF is the DF for the likelihood ratio test? Is there any smart way to compare models in proc surveylogistic? Thank you!
... View more
