Programming the statistical procedures from SAS

categorical data in glimmix

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categorical data in glimmix

Hello all,

I've a data set including two fixed factors (house, strain) with 3 levels of each. The response variable is a lameness score of birds with scores ranging from 0 to 4 (0, 1, 2, 3, 4). I wanted to know if there is a effect of house and/or strain for each score separately. I considered using glimmix with following code

proc glimmix data=work;

class house strain;

model score=house strain/dist=multinomial link=glogit ;

estimate 'A vs B' house 1 -1/ bycat;

estimate 'A vs C' house 1 0 -1/ bycat;

estimate 'B Vs C' house 0  1 -1/ bycat;

estimate 'D vs E' strain 1 -1/ bycat;

estimate 'D vs F' strain 1 0 -1/ bycat;

estimate 'E vs F' strain 0  1 -1/ bycat;

run;

However Sas keeps giving me wrong degrees of freedom for main effects and i think the whole analysis was wrong. It would be of great help if somebody could tell me what i'm doing wrong or what would be the appropriate code...

thaks

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Posts: 2,655

Re: categorical data in glimmix

Well, assuming no interaction, something odd is happening.  By specifying link=glogit, you should be getting nominal data, and the estimates should be correct--if everything else is working.  So some design questions: I assume 3 houses and 3 strains.  How many observations are available?  What degrees of freedom are coming up in the output?  Maybe with those we can identify the source of the oddness.

Steve Denham

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