[R] need help with chisq

[Stephanie Kovalchik]

JC,

If each row are the counts for a 2 x 2 contingency table - so for the  
ith contingency table you have counts for row 1 c(Y08[i],Z08[i]) and  
row 2 (Y09[i],Z09[i]) then you could use apply:

X <- cbind(vdata$Y08,vdata$X08-vdata$Y08,vdata$Y09,vdata$X09-vdata$Y98)

f.chisq <- function(x){
m <- matrix(x,2,2)
chisq.test(m)$p.value
}

apply(X,1,f.chisq)



Quoting JC <jerome.coste at gmail.com>:

>
> I am very new to R. I have some data from a CVS stored in vdata with 4
> columns labeled:
> X08, Y08, X09, Y09.
>
> I have created two new "columns" like so:
>
> Z08 <- (vdata$X08-vdata$Y08)
>
> Z09 <- (vdata$X09-vdata$Y09)
>
> I would like to use chisq.test for each "row" and output the p-value
> for each in a stored variable. I don't know how to do it. Can you
> help?
>
> so far I have done it for one row (but I want it done automatically
> for all my data):
>
> chidata=rbind(c(vdata$Y08[1],Z08[1]),c(vdata$Y09[1],Z09[1]))
> results <- chisq.test(chidata)
> results$p.value
>
> I tried removing the [1] and the c() but that didn't work...  Any
> ideas?
>
> THANKS!
>
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