topic The class statement with PROC MDC in Statistical Procedures

The class statement with PROC MDC

Demographer — Fri, 07 Aug 2015 17:49:10 GMT

I think there is a problem with the class statement using proc MDC (type=mixedlogit). In the results, there is a parameter for the reference value, which is a non-sense. Moreover, this parameter has no standard error. I really don't get why. I know I could just create dummy variables, but I want to be sure that it's not another problem. Thanks.

Re: The class statement with PROC MDC

Rick_SAS — Fri, 07 Aug 2015 19:27:55 GMT

Could you share the syntax and output? Perhaps on a SASHELP or a simulated data set so we can all see the problem?

Re: The class statement with PROC MDC

Demographer — Fri, 07 Aug 2015 19:45:29 GMT

I work in a secure lab so I can't copy/paste the syntax. The syntax was basic, such as:

Suppose variable "a" has 3 categories.

proc mdc;

class=a;

model y = a b c/

type=mixedlogit nchoice=10 mixed=(normalparm=a);

id id;

run;

The output is normal for the other variables. The only major bug is that there is a parameter for the reference value of the variable "a" and that parameter doesn't have standard error.

Re: The class statement with PROC MDC

Rick_SAS — Fri, 07 Aug 2015 20:21:02 GMT

Your syntax doesn't correctly specify the reference parameterization. You need to say

class a(ref='1') / param=ref;

where '1' should be replaced by whatever level you want to use for the reference level.

Re: The class statement with PROC MDC

Demographer — Fri, 07 Aug 2015 20:27:00 GMT

Those commands are not supported by PROC MDC. See there:

Re: The class statement with PROC MDC

Rick_SAS — Fri, 07 Aug 2015 21:11:31 GMT

I apologize. I'd go to tech support with this one. The documentation doesn't even mention the syntax you are using.

Re: The class statement with PROC MDC

Demographer — Fri, 07 Aug 2015 21:34:56 GMT

I think the documentation is not up to date. The class statement with proc MDC works with SAS 9.4 (with the bug mentionned above), but is not supported with SAS 9.1.