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08-21-2015 12:23 PM

Hello everyone,

I am applying PROC GLIMMIX on a dataset with binary response. I am getting a NOTE in the log file which is:

NOTE: Some observations are not used in the analysis because of: missing subject effects (n=2), not a proportion (n=142).

In the output page I get either "Does not converge" or "Estimated G matrix is not positive definite." I'm thinking that I have these problems since more than half of observations are deleted as the LOG file says (total sample size is 214). I've been digging the whole internet, but no one talked about this NOTE! I was wondering if anyone can help me over here.

my cods are:

proc glimmix data = colaps ;

class id;

model knowledge1_23 = prepost / s dist = binomial link = logit;

random int / subject = id ;

run;

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Solution

08-21-2015
01:16 PM

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08-21-2015 01:16 PM

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08-21-2015 12:48 PM

What do you see if you run the following procedures?

proc means data=colaps N NMISS;

var id;

run;

proc freq data = colaps;

tables knowledge1_23;

run;

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08-21-2015 12:55 PM

Hello Rick, Thanks.

These are the results:

n nmiss

214 0

knowledge1_23 frequency

1 72

2 142

Solution

08-21-2015
01:16 PM

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08-21-2015 01:16 PM

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08-21-2015 01:27 PM

Thanks to both of you.

That's correct! I had no idea that response should be 0s and 1s! Thanks.

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08-21-2015 02:01 PM

Be aware that GLIMMIX supports a BINARY (=Bernoulli) distribution and a BINOMIAL distribution (for proportions),

You are using the binomial distribution, which requires 0/1.

If you meant to use a binary distribution, then '1' and '2' are perfectly OK, because any binary variable will work:

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08-21-2015 02:30 PM

I see! Thanks for your helpful comments.

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08-21-2015 01:39 PM

Apparently one of the subjects (with 2 repeated measurements) has missing values for some variable, but I'm

confused because in my version of SAS the NOTE in the log also says "missing fixed effects (n=2)" for that case. That's why I didn't ask about PREPOST. But maybe you have an earlier version of SAS in which the NOTE was different.