Hi Steve I tried this and compare the outcome for three approaches: 1) using link=log for the data transformation 2) compared to non-transformed data 3) compare to the result with taking log transformation before fitting the model. Here is my finding: 1 and 2 approaches got exactly the same output. 1 and 3 doesn't agree (not what I have expected...). **Orignial Variable with Link=log**; ods graphics on; proc glimmix data=sub method=laplace namelen=50 plots=STUDENTPANEL; nloptions maxiter=100; format &exp. &expf..; class &exp. (ref="&expref.") ; weight discwt; model los = &exp. /solution link=log ; lsmeans &exp. /ilink; title ""; run; ods graphics off; **Not transformed**; ods graphics on; proc glimmix data=sub method=laplace namelen=50 plots=STUDENTPANEL; nloptions maxiter=100; format &exp. &expf..; class &exp. (ref="&expref.") ; weight discwt; model los = &exp. /solution; lsmeans &exp.; title ""; run; ods graphics off; **Take log transformation before fit the model***; proc glimmix data=sub method=laplace namelen=50; nloptions maxiter=100; format &exp. &expf.. ; class &exp. (ref="&expref.") ; weight discwt; model log_los = &exp. /solution; lsmeans &exp.; title ""; run; Thanks Steven
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