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Re: R MATRIX ALGORITHMICALLY SINGULAR

From: wangx826
Date: 09 Sep 2009 22:00:55 -0500

Hi Susan,

The most common reason is that you got too many parameters. But if there is
someone who could summarize all other possible reasons for this kind of
error, it would be really appreciated.
If your model is not over-parameterized, there's one way to avoid it. You
could try adding "Matrix=S" into $COV block. This would give you a similar
estimate of covariance matrix if your sample size is large enough.
Hope it helps,

Tianli
****************************************************
Tianli Wang
PhD Candidate
Department of Pharmaceutics
University of Minnesota

On Sep 9 2009, Hudachek,Susan wrote:

> Greetings! I have run several models and the covariance steps have been
> unsuccessful due to the following error:
>
>R MATRIX ALGORITHMICALLY SINGULAR
>COVARIANCE MATRIX UNOBTAINABLE
>R MATRIX IS OUTPUT
>T MATRIX - EQUAL TO RS*R, WHERE S* IS THE INVERSE OF S - IS OUTPUT
>
> Does anyone have an idea as to what this indicates and how to 'fix" it?
> Thanks in advance for any help/input you can offer!
>Susan
>
>Susan Hudachek, M.S., Ph.D.
>Animal Cancer Center
>Veterinary Teaching Hospital
>Colorado State University
>300 West Drake Road
>Fort Collins, CO 80523-1620
>PHONE: (970) 219-7599
>FAX: (970) 297-1254
>EMAIL: Susan.Hudachek
>
Received on Wed Sep 09 2009 - 23:00:55 EDT

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