categorical data in glimmix

Poultry — Thu, 09 Oct 2014 20:59:28 GMT

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

Re: categorical data in glimmix

SteveDenham — Tue, 14 Oct 2014 11:54:28 GMT

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

topic categorical data in glimmix in Statistical Procedures

categorical data in glimmix

Re: categorical data in glimmix