Turn on suggestions

Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type.

Showing results for

- Home
- /
- Analytics
- /
- Stat Procs
- /
- Not a proportion?? PROC GLIMMIX

Options

- RSS Feed
- Mark Topic as New
- Mark Topic as Read
- Float this Topic for Current User
- Bookmark
- Subscribe
- Mute
- Printer Friendly Page

🔒 This topic is **solved** and **locked**.
Need further help from the community? Please
sign in and ask a **new** question.

- Mark as New
- Bookmark
- Subscribe
- Mute
- RSS Feed
- Permalink
- Report Inappropriate Content

Posted 08-21-2015 12:23 PM
(3873 views)

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;

1 ACCEPTED SOLUTION

Accepted Solutions

- Mark as New
- Bookmark
- Subscribe
- Mute
- RSS Feed
- Permalink
- Report Inappropriate Content

7 REPLIES 7

- Mark as New
- Bookmark
- Subscribe
- Mute
- RSS Feed
- Permalink
- Report Inappropriate Content

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;

- Mark as New
- Bookmark
- Subscribe
- Mute
- RSS Feed
- Permalink
- Report Inappropriate Content

Hello Rick, Thanks.

These are the results:

n nmiss

214 0

knowledge1_23 frequency

1 72

2 142

- Mark as New
- Bookmark
- Subscribe
- Mute
- RSS Feed
- Permalink
- Report Inappropriate Content

- Mark as New
- Bookmark
- Subscribe
- Mute
- RSS Feed
- Permalink
- Report Inappropriate Content

Thanks to both of you.

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

- Mark as New
- Bookmark
- Subscribe
- Mute
- RSS Feed
- Permalink
- Report Inappropriate Content

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:

- Mark as New
- Bookmark
- Subscribe
- Mute
- RSS Feed
- Permalink
- Report Inappropriate Content

I see! Thanks for your helpful comments.

- Mark as New
- Bookmark
- Subscribe
- Mute
- RSS Feed
- Permalink
- Report Inappropriate Content

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.

Build your skills. Make connections. Enjoy creative freedom. Maybe change the world. **Registration is now open through August 30th**. Visit the SAS Hackathon homepage.

What is ANOVA?

ANOVA, or Analysis Of Variance, is used to compare the averages or means of two or more populations to better understand how they differ. Watch this tutorial for more.

Find more tutorials on the SAS Users YouTube channel.