[R] need help for chi-squared test

[David Winsemius]

On Jan 6, 2011, at 1:23 PM, kiotoqq wrote:

>
> I've got a dataset which looks like this in the beginning:
>
>
>     cbr  dust smoking expo
> 1      0  0.20       1    5
> 2      0  0.25       1    4
> 3      0  0.25       1    8
> 4      0  0.25       1    4
> 5      0  0.25       1    4
>
> (till no. 1240, anyway, a huge set)
>
> I have to analyse cbr and smoking, I know it works with chisq.test()  
> for the
> whole set, but I only need cbr and smoking, and I have no idea how to
> extract them.

This is not a sufficiently complex example on which to offer a  
solution, nor is it even clear enough to understand definitively what  
you want. So here is a guess:

dfrm[which(dfrm$cbr==1 & dfrm$smoking==1), ]

... which would return a dataframe (or matrix depending on what form  
that data exists in) with only those cases where thos two conditions  
hold. You can either assign this value to an R object or you can apply  
the chisq.test() in what ever (unstated) manner you think has been  
"working" to the returned value as a whole.

Please read the message at the bottom and follow its encouragement to  
read the Posting Guide.

> -- 
> View this message in context: http://r.789695.n4.nabble.com/need-help-for-chi-squared-test-tp3177925p3177925.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

David Winsemius, MD
West Hartford, CT