R help - Sep 2013 - Permutation Test on Interactions {coin}

Dear List,

I'm interested in performing a permutation test on the interaction between
a binary treatment indicator and a covariate (either continuous or
categorical). I'm interested in the p-value of the interaction effect from
a permutation test, and I'm using the coin package for that purpose.

As I haven't seen any examples like this in the package documentation (or
anywhere else), I'm not sure how to specify the test in this case. For
example, should I interpret the p-value in the example below as the pvalue
of the interaction effect between group and the covariate x.

set.seed(1)
library("coin")
data("rotarod", package = "coin")
x <- rnorm(24)
rotarod <- cbind(rotarod, x)
pvalue(independence_test(time ~ group * x, data = rotarod))


Your advice would be much appreciated.

Regards,
Axel.

	[[alternative HTML version deleted]]

Axel,

you need a model for such type of analyses and coin is completely 
model-free.

Torsten

On Mon, 23 Sep 2013, Axel Urbiz wrote:
> Dear List,
> I'm interested in performing a permutation test on the interaction
between a binary treatment
> indicator and a covariate (either continuous or categorical). I'm
interested in the p-value
> of the interaction effect from a permutation test, and I'm using the
coin package for that
> purpose.?
> 
> As I haven't seen any examples like this in the package documentation
(or anywhere else), I'm
> not sure how to specify the test in this case. For example, should I
interpret the p-value in
> the example below as the pvalue of the interaction effect between group and
the covariate x.?
> 
> set.seed(1)
> library("coin")
> data("rotarod", package = "coin")
> x <- rnorm(24)
> rotarod <- cbind(rotarod, x)
> pvalue(independence_test(time ~ group * x, data = rotarod))
> 
> 
> Your advice would be much appreciated.?
> 
> Regards,
> Axel. ??
> 
>