SAS Proc mdc : The CHOICE= variable contains redundant alternatives ? (Degenerate case)

Question

I am estimating a Nested Logit model in SAS.

• Upper level : Two options 1 and 2
• Lower level : 1 has sub-options 1 and 2; and 2 has sub-option 0 ( degenerate case)
• Explanatory variables x1,x2,x3,x4,x5 are common to all alternatives(0,1,2)

proc mdc data=c7.nlm;
   model chosen = x1 x2 x3 x4 x5 /
            type=nlogit
            choice=(mode 0 1 2)
            covest=hess;
   id cocode;
   utility u(1,) = x1 x2 x3 x4 x5;
nest level(1) = (1 2 @ 1, 0 @ 2),
        level(2) = (1 2 @ 1);
run; 

Code as per documentation here

I get an error : ERROR: The CHOICE= variable contains redundant alternatives

What could be going wrong here?

Thanks in advance,

Answer 1

Your lucky day.

Usage Note 34785: What causes the error "The CHOICE= variable contains redundant alternatives" in PROC MDC?

http://support.sas.com/kb/34/785.html