Dear John,
Yes. Assuming that 'sample2' is fixed, something like this should do what
you want:

# Data sets
set.seed(123)
sample1=matrix(rnorm(100),ncol=10)
sample2=rnorm(10,5,4)

# t-test p-values
apply(X,1,function(x) t.test(x,sample2)$p.value)
[1] 0.002348970 0.004733230 0.004810952 0.004907549 0.002342979 0.018748229
0.003546655 0.006084410
 [9] 0.003100983 0.007007980


HTH,

Jorge


On Thu, Oct 16, 2008 at 8:01 AM, John Sorkin <jsorkin@grecc.umaryland.edu>wrote:

> R 2.7.2
> Windows XP
>
> I am using apply to compute a series of Student's t-test from two matrices,
> sample1 and sample2.
> boo<-apply(sample1,1,t.test,sample2)
>
>  I want to pick of the p-values from the tests, but can't seem to get it to
> work. I have tried several methods to get the values including:
> boo<-apply(sample1,1,t.test$t.test,sample2)
> boo<-apply(sample1,1,t.test,sample2)$t.test
>
> any suggestions?
>
> Thanks
> John
>
> John Sorkin M.D., Ph.D.
> Chief, Biostatistics and Informatics
> Baltimore VA Medical Center GRECC,
> University of Maryland School of Medicine Claude D. Pepper OAIC,
> University of Maryland Clinical Nutrition Research Unit, and
> Baltimore VA Center Stroke of Excellence
>
> University of Maryland School of Medicine
> Division of Gerontology
> Baltimore VA Medical Center
> 10 North Greene Street
> GRECC (BT/18/GR)
> Baltimore, MD 21201-1524
>
> (Phone) 410-605-7119
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