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Date:         Wed, 11 Oct 2006 06:05:25 -0400
Reply-To:     Peter Flom <flom@NDRI.ORG>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Peter Flom <flom@NDRI.ORG>
Subject:      Re: Hypergeometric distribution
Comments: To: c_kenaszchuk@YAHOO.CA
Content-Type: text/plain; charset=US-ASCII

>>> <c_kenaszchuk@YAHOO.CA> 10/10/06 8:57 PM >>> wrote <<< Anyone familiar with Zelterman book, "Advanced Log-Linear Models Using SAS"? I'm looking for help with Program 8.2 from the book. This program fits a model to a stratified 2x2 table with the hypergeometric distribution, and Prof. Zelterman's macros appearing in Program 8.4. >>>

I have it, and have read it (I thought it quite good) but I don't have it handy. Others may not have it at all. Why not post the code here?

<<< I'm attempting to use the published programs to estimate the model. Basic problem is that the model fails to converge. No problem with the code; it's copied and pasted correctly from the SAS companion web site into my data editor. It runs correctly with the supplied sample data. I suspect a problem with my data and, probably, the appropriateness of this model for my data. Error message in the log are these:

WARNING: The specified model did not converge. ERROR: Error in computing the link function, its derivatives, or the variance function. NOTE: The scale parameter was held fixed. ERROR: Negative variance from user-defined variance function.ERROR: Invalid Operation. >>>

Well, without knowing anything about your data, and without the program to look at, how can we tell? Clearly, the program doesn't work for you data, beyond that.....

The scale parameter being fixed.......well......it MIGHT mean you need to consider some other distribution.....but it's really hard to say. One thing you might want to look at it is the iterations history.

Why don't you write back to SAS-L, not just pasting in the code, but describing your data, how many variables, their nature, is it a survey or observational study or what? What are you investigating? What is sample size?

etc,

Then someone here may be able to help you

Peter


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