Dummy variables in logistic regression models

Why do switching of values in a dummy variable and the use of class statement in PROC LOGISTIC change the coefficients in logistic regression?

(1) and (2) produce the same results. (3) and (4) produce the same results.

(1)
proc logistic data=here.asdf descending ;
model college= boy ;
run;

(2)
proc logistic data=here.asdf descending ;
class girl;
model college= girl ;
run;

(3)
proc logistic data=here.asdf descending ;
model college= girl;
run;

(4)
proc logistic data=here.asdf descending ;
class boy;
model college= boy ;
run;

(1) Estimates (2) Estimates (3) Estimates (4) Estimates
Intercept

0.5346

 Intercept

0.3645

 Intercept

0.1945

 Intercept

0.3645

boy      

-0.3401

 girl    

-0.1701

 girl

0.3401

 boy      

0.1701

               
Odds ratio

0.712

 

0.712

 

1.405

 

1.405

Leave a Reply