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Re: st: Logistic regression interpretation


From   Michael Morrison <Morrimic@niacc.edu>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Logistic regression interpretation
Date   Tue, 21 Sep 2010 17:04:55 -0500

I recommend you read Long & Freese (2006) /Regression Models for Categorical Dependent Variables Using Stata. It provides interpretation of odds, _controlling for covariates_ and ways to test your model's goodness of fit. Also of interest is their Spost commands.

Mike

/

On 9/21/2010 4:36 PM, Dr. Bill Westman wrote:
Dear Listers: I have more of a stats question than a stata question,
but here goes:

A simple logistic regression was run - outcome - Survived/Non Survived
(1/0), with Group(Treatmeant/Control -- 1/0)&  Risk(High/Low -- 1/0)

The results
------------------------------------------------------------------------------
        Survived | Odds Ratio   Std. Err.      z    P>|z|     [95%
Conf. Interval]
-------------+----------------------------------------------------------------
     Risk |   4.790295   2.589136     2.90   0.004     1.660699    13.81763
    group |   2.111181   .9107981     1.73   0.083     .9063649    4.917538
------------------------------------------------------------------------------

Assuming the .10 level of significance was acceptable (for discussion purposes)

Can I assume that odds of treatment survival were 2.1  times higher in
the treatment Group for LOW risk patients?
And for High Risk patients in the treatment group is the adds 4. 8 +
2.1 (or 6 times higher)?

Other than test for interactions, can I run a graphs of these two groups?

Can I estimate the "average" effect of Treatment across both high and
low risk patients?  If so, how?

What other tests might I wish to do in Stata?

Thanks

Bill
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