[R] comparing strength of association instead of strength of evidence?

From: Weiwei Shi <helprhelp_at_gmail.com>
Date: Sat 25 Jun 2005 - 00:59:13 EST


Hi,
I asked this question before, which was hidden in a bunch of questions. I repharse it here and hope I can get some help this time:

I have 2 contingency tables which have the same group variable Y. I want to compare the strength of association between X1/Y and X2/Y. I am not sure if comparing p-values IS the way even though the probability of seeing such "weird" observation under H0 defines p-value and it might relate to the strength of association somehow. But I read the following statement from Alan Agresti's "An Introduction to Categorical Data Analysis" : "Chi-squared tests simply indicate the degree of EVIDENCE for an association....It is sensible to decompose chi-squared into components, study residuals, and estimate parameters such as odds ratios that describe the STRENGTH OF ASSOCIATION".

Can I do this "decomposition" in R for the following example including 2 contingency tables?

> tab1<-array(c(11266, 125, 2151526, 31734), dim=c(2,2))
> tab1

      [,1] [,2]
[1,] 11266 2151526
[2,] 125 31734

> tab2<-array(c(43571, 52, 2119221, 31807), dim=c(2,2))
> tab2

      [,1] [,2]
[1,] 43571 2119221
[2,] 52 31807

BTW, is there some good forum on the theory of statistics? r-help is a good one but I don't want to bother people by asking some questions weakly associated with R here.

Thanks,

-- 
Weiwei Shi, Ph.D

"Did you always know?"
"No, I did not. But I believed..."
---Matrix III

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Received on Sat Jun 25 01:01:55 2005

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