mantelhaen.test for more than two groups?

From: Peter Dalgaard <p.dalgaard at biostat.ku.dk>
To: Thomas Lumley <tlumley at u.washington.edu>
CC: Katrin Schweitzer <Katrin.Schweitzer at ims.uni-stuttgart.de>,        
r-help at stat.math.ethz.ch
Subject: Re: [R] mantelhaen.test for more than two groups?
Date: 26 Apr 2005 18:24:31 +0200

Thomas Lumley <tlumley at u.washington.edu> writes:

On Tue, 26 Apr 2005, Katrin Schweitzer wrote:

Dear All,

I'd like to perform the generalized Cochran-Mantel-Haenszel-Test (as
described in Agresti (1990), Categorical Data Analysis) for my
nominal data.

My problem is that I have more than two groups. In fact I think I'd
need an 5-dimensional array for the response variable, the control
variable and three group variables.
Could you please tell me if this is possible in R - and if yes how I
am supposed to do this?

You're supposed to have a three-dimensional array: exposure x response
x group.

This means turning your three group variables into one variable.  One
way to do this is with the interaction() function.

Or, if data are already counts, change the dimensions (as in dim(x) <-
c(2,3,8)), possibly after using aperm() to get the indices in the
right order.

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   O__  ---- Peter Dalgaard             Blegdamsvej 3
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