I am new to using the "class" statement in Proc Logistic. The output from Proc Logistic using the class statement does not order the Odds ratios in the order of the format or label. The data is looking at pack years of smoking and whether there is a dose response with pack years and cancer. My format is Value pkyrcat3f 1='never cig smk'                   2='<20 pkyrs'                   3='20-<40'                   4='>=40'; The labels are if packy =0 then  pkyrcat3= 1; else if packy >0 and packy <20.00 then pkyrcat3=2; else if packy >=20.00 and packy <40.00 then pkyrcat3=3;else if packy >=40.00 then pkyrcat3=4; Here is the Proc logistic call: Note: when I used FIRST as the REF for PKYRCAT3, the referent was >=40 years, so I changed the referent to last and the NEVER smoked category became the referent, which is the correct referent group. proc logistic data=pan2.pkyr; /*1=case, 2= control*/ class age10yg(ref=first)sex race educat (ref=last) bmiad3cat (ref=first) etoh(ref=first) diabetes(ref=last) pancreat(ref=last) pkyrcat3(ref=last) / param=ref; model status= age10yg sex race educat bmiad3cat etoh diabetes pancreat hisp gb_stones pkyrcat3  / selection = forward include=11 ctable pprob= (0 to 1 by .1) outroc=roc; run; quit; From the output the automatically coded dummy variables are: pkyrcat3 20-<40 1 0 0 <20 pkyrs 0 1 0 >=40 0 0 1 never cig smk 0 0 0 The correct order is as shown in the label. How can the correct order be obtained using the CLASS statement? Does the order NOT MATTER in the Odds Ratio result for looking at dose-response?  How can the variable be coded in the correct order using the CLASS statement versus creating manual dummy variables?  Thank you. ... View more