R help - Nov 2010 - cross tabulate variables by subject id

Dear list,

I have data like this:

dat1 <- data.frame(subject=rep(1:10,2),
                   cond1=rep(c("A","B"),each=5),
                   cond2=rep(c("C","D"),each=10),
                   choice=sample(0:1,10,replace=TRUE))

I would like to compare subjects' "choice" for
(cond1=="A" &
cond2=="C") vs (cond1=="A" & cond2=="D"),
using mcnemar.test

The ?mcnemar.test example has the data in a matrix:

     Performance
            2nd Survey
1st Survey   Approve Disapprove
  Approve        794        150
  Disapprove      86        570


So for my case, I need something like:

   Choice
         AC
AD	 0	1
  0     ...
  1

Where "..." would be the sum of subjects who answered 0 or 1 to AC
and/or AD respectively.

I can get the first step by making an extra variable:

dat1$condnew <- paste(dat1$cond1,dat1$cond2,sep="")

although I am sure there are more elegant ways, and especially, I am
stumped how to fill in the cells of the table.

Thanks,

Marianne

-- 
Marianne Promberger PhD, King's College London
http://promberger.info
R version 2.12.0 (2010-10-15)
Ubuntu 9.04

Hi Marianne,

How about this...

ac.ad <- unstack(dat1, choice ~ cond1:cond2)[, c("A.C",
"A.D")]
acad.xtab <- with(ac.ad, table(A.C, A.D))

Michael


On 29 November 2010 20:18, Marianne Promberger
<marianne.promberger at kcl.ac.uk> wrote:
> Dear list,
>
> I have data like this:
>
> dat1 <- data.frame(subject=rep(1:10,2),
> ? ? ? ? ? ? ? ? ? cond1=rep(c("A","B"),each=5),
> ? ? ? ? ? ? ? ? ? cond2=rep(c("C","D"),each=10),
> ? ? ? ? ? ? ? ? ? choice=sample(0:1,10,replace=TRUE))
>
> I would like to compare subjects' "choice" for
(cond1=="A" &
> cond2=="C") vs (cond1=="A" & cond2=="D"),
using mcnemar.test
>
> The ?mcnemar.test example has the data in a matrix:
>
> ? ? Performance
> ? ? ? ? ? ?2nd Survey
> 1st Survey ? Approve Disapprove
> ?Approve ? ? ? ?794 ? ? ? ?150
> ?Disapprove ? ? ?86 ? ? ? ?570
>
>
> So for my case, I need something like:
>
> ? Choice
> ? ? ? ? AC
> AD ? ? ? 0 ? ? ?1
> ?0 ? ? ...
> ?1
>
> Where "..." would be the sum of subjects who answered 0 or 1 to
AC
> and/or AD respectively.
>
> I can get the first step by making an extra variable:
>
> dat1$condnew <- paste(dat1$cond1,dat1$cond2,sep="")
>
> although I am sure there are more elegant ways, and especially, I am
> stumped how to fill in the cells of the table.
>
> Thanks,
>
> Marianne
>
> --
> Marianne Promberger PhD, King's College London
> http://promberger.info
> R version 2.12.0 (2010-10-15)
> Ubuntu 9.04
>
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