[R] R equivalent of SAS Cochran-Mantel-Haenszel tests?
vito muggeo
vmuggeo at dssm.unipa.it
Mon Feb 9 16:46:44 CET 2009
Dear Michael,
It sounds as a linear-by-linear loglinear model (and its variants) which
uses scores for one or more variables in the table.. (see Agresti, 1990,
Categorical Data Analysis. I do remember the pages and I have not the
book here..)
If this is the case, you can use standard call to glm(..,
family=poisson) with score variables in the linear predictor. For
instance for a two-way table with ordered variables the linear-by-linear
model is,
glm(freq~factor(x)+factor(y)+I(score.x*score.y), family=poisson)
The CMH test, probably, is the score test of the parameter of
I(score.x*score.y)..
best,
vito
Michael Friendly ha scritto:
> In SAS, for a two-way (or 3-way, stratified) table, the CMH option in
> SAS PROC FREQ gives
> 3 tests that take ordinality of the factors into account, for both
> variables, just the column variable
> or neither. Is there an equivalent in R?
> The mantelhaen.test in stats gives something quite different (a test of
> conditional independence for
> *nominal* factors in a 3-way table).
>
> e.g. I'd like to reproduce:
> *-- CMH tests;
> proc freq data=sexfun order=data;
> weight count;
> tables husband * wife / cmh chisq nocol norow;
> run;
>
> The FREQ Procedure
> Summary Statistics for Husband by Wife
> Cochran-Mantel-Haenszel Statistics (Based on Table Scores)
>
> Statistic Alternative Hypothesis DF Value Prob
>
> 1 Nonzero Correlation 1 10.0142 0.0016
> 2 Row Mean Scores Differ 3 12.5681 0.0057
> 3 General Association 9 16.7689 0.0525
>
--
====================================
Vito M.R. Muggeo
Dip.to Sc Statist e Matem `Vianelli'
Università di Palermo
viale delle Scienze, edificio 13
90128 Palermo - ITALY
tel: 091 6626240
fax: 091 485726/485612
http://dssm.unipa.it/vmuggeo
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