[R] by group testing

[Joshua Wiley]

On Wed, Aug 4, 2010 at 10:17 AM, Joshua Wiley <jwiley.psych at gmail.com> wrote:
> Hello,
>
> This will put the results of the Fisher test in a list, with each
> element of the list being the results for mouse type a, b, c, and d.
>
> mice <- rep(letters[1:4],10)
> outcome <- sample(c(0,1),length(mice),replace=T)
> group <- c(rep("A",length(mice)/2),rep("B",length(mice)/2))
>
> my.data <- data.frame(mice,outcome,group)
>
> results <- lapply(split(x = my.data, f = my.data$mice), function(dat) {
>  fisher.test(x = dat[, "outcome"], y = dat[, "group"])
> })

or similarly, using by()...

results2 <- by(data = my.data, INDICES = my.data$mice, FUN = function(dat) {
    fisher.test(x = dat[, "outcome"], y = dat[, "group"])
  })

results2$a
results2$b

>
> results$a #mouse type a
> results$b #b, etc.
>
> Cheers,
>
> Josh
>
> On Wed, Aug 4, 2010 at 9:27 AM, cheba meier <cheba.meier at googlemail.com> wrote:
>> Hello,
>>
>> I have a data set which is similar to the following data
>>
>> mice <- rep(letters[1:4],10)
>> outcome <- sample(c(0,1),length(mice),replace=T)
>> group <- c(rep("A",length(mice)/2),rep("B",length(mice)/2))
>>
>> my.data <- data.frame(mice,outcome,group)
>> my.sort.data <- my.data[order(my.data[,1]),]
>>
>> I would like to test wether there is a different between group A and B for
>> each mause type!
>>
>> I was trying to use by, table and fisher.test/prop.test functions to do
>> this, but I could not solve this problem, any suggestion?
>>
>> Many thanks in advance,
>> Cheba
>>
>>        [[alternative HTML version deleted]]
>>
>> ______________________________________________
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>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
>
>
> --
> Joshua Wiley
> Ph.D. Student, Health Psychology
> University of California, Los Angeles
> http://www.joshuawiley.com/
>



-- 
Joshua Wiley
Ph.D. Student, Health Psychology
University of California, Los Angeles
http://www.joshuawiley.com/