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# st: Re: Cochran Mantel Haenszel Statistic

 From Robert A Yaffee To statalist@hsphsun2.harvard.edu Subject st: Re: Cochran Mantel Haenszel Statistic Date Wed, 22 Sep 2010 08:46:43 -0400

```Hi,
Has any attempted to write a Cochran Mantel-Haenszel Statistic for the homogeneity of stratified crosstabulations?
Robert

Robert A. Yaffee, Ph.D.
Research Professor
Silver School of Social Work
New York University

Biosketch: http://homepages.nyu.edu/~ray1/Biosketch2009.pdf

CV:  http://homepages.nyu.edu/~ray1/vita.pdf

----- Original Message -----
From: Maarten buis <maartenbuis@yahoo.co.uk>
Date: Wednesday, September 22, 2010 5:23 am
Subject: Re: st: RE: Logistic regression interpretation
To: statalist@hsphsun2.harvard.edu

> --- On Wed, 22/9/10, Kieran McCaul wrote:
> > low risk, control group: OR=1.00 (ref)
> > high risk, control group: OR=2.11
> > low risk, treatment group: OR=4.79
> > high risk, treatment group: OR=2.11*4.79=10.11
>
>
> --- I wrote:
> > There are no interactions so the odds increases
> > with a factor 2.1 when one receives the treatment
> > regardless of whether one is in the high or
> > low risk group
>
> These two statements appear to be a contradiction,
> but they are not. The difference is in what we define
> as our reference group.
>
> I compared control versus treatment both in high risk
> group and control versus treatment both in the low
> risk group. This is how I think of "controlling for
> a variable".
>
> Kieran compared all groups with the low risk control
> group.
>
> As always, an effect is just a comparison of groups,
> of reference group accordingly.
>
> Hope this helps,
> Maarten
>
> --------------------------
> Maarten L. Buis
> Institut fuer Soziologie
> Universitaet Tuebingen
> Wilhelmstrasse 36
> 72074 Tuebingen
> Germany
>
> http://www.maartenbuis.nl
> --------------------------
>
>
>
>
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```