topic Surveylogistic Question in SAS Procedures https://communities.sas.com/t5/SAS-Procedures/Surveylogistic-Question/m-p/127745#M34931 <HTML><HEAD></HEAD><BODY><P>Hi everyone-<SPAN style="font-size: 10pt; line-height: 1.5em;">I have two different logistic models, call them Model A and Model B.&nbsp; They are exactly the same, except Model B has some additional interactions added as predictors.&nbsp; I would like to determine whether the additional predictors in Model B are significant as a whole.&nbsp; Is there a way to do this in SAS?</SPAN></P></BODY></HTML> Tue, 05 Mar 2013 17:50:13 GMT alanb4173 2013-03-05T17:50:13Z Surveylogistic Question https://communities.sas.com/t5/SAS-Procedures/Surveylogistic-Question/m-p/127745#M34931 <HTML><HEAD></HEAD><BODY><P>Hi everyone-<SPAN style="font-size: 10pt; line-height: 1.5em;">I have two different logistic models, call them Model A and Model B.&nbsp; They are exactly the same, except Model B has some additional interactions added as predictors.&nbsp; I would like to determine whether the additional predictors in Model B are significant as a whole.&nbsp; Is there a way to do this in SAS?</SPAN></P></BODY></HTML> Tue, 05 Mar 2013 17:50:13 GMT https://communities.sas.com/t5/SAS-Procedures/Surveylogistic-Question/m-p/127745#M34931 alanb4173 2013-03-05T17:50:13Z Re: Surveylogistic Question https://communities.sas.com/t5/SAS-Procedures/Surveylogistic-Question/m-p/127746#M34932 <HTML><HEAD></HEAD><BODY><P>The best way to test as a whole would be to do a likelihood ratio test.&nbsp; Since Model A is completely nested in Model B, the difference in the -2 log likelihoods should be asymptotically distributed as chi-squared with df=number of additional parameters.&nbsp; ODS OUTPUT is your friend for getting the likelihoods into datasets where you can manipulate the values and do the calculations.&nbsp; Oh, and I forgot this, everything between Model A and B has to really, really be exactly the same--no changes in PSUs or sampling weights.</P><P></P><P>Steve Denham</P></BODY></HTML> Tue, 05 Mar 2013 20:51:19 GMT https://communities.sas.com/t5/SAS-Procedures/Surveylogistic-Question/m-p/127746#M34932 SteveDenham 2013-03-05T20:51:19Z