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10-16-2015 12:20 PM

Dear all,

If you have binomial data for which the group sizes differ, how do you correct for it in proc glimmix?

For example:

proc glimmix data=name;

class var1 var2;

model y/n=var1 var2 / dist=binomial link=logit;

random randomvariable;

run;

y is for example the number of affected individuals per group that differs in size (n). I have been told that you can correct for this by adding an overdispersion parameter 'random _residual_;' but I am not too confident about this. Anyone have any ideas? Thanks in advance.

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10-16-2015
05:23 PM

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10-16-2015 03:03 PM

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Solution

10-16-2015
05:23 PM

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10-16-2015 03:03 PM

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10-16-2015 03:26 PM

Agree. And further, since the random-statement is not neccessary, it may be better to use a procedure (proc logistics) that is specialized for logistic regression.

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10-16-2015 05:27 PM - edited 10-16-2015 05:27 PM

Thanks, thought it was a bit weird to correct for unequal sizes using an overdispersion parameter. Good to hear a confirmation that it is not necessary to do so.