[R] Non-parametric four-way interactions?

[Paul Smith]

On 7/27/06, Frank E Harrell Jr <f.harrell at vanderbilt.edu> wrote:
> Tony Lachenbruch has written some about this, also see my book (it's web
> page is biostat.mc.vanderbilt.edu/rms).  I don't know about the power of
> interaction tests, but for main effect tests in the absence of
> interaction, the Wilcoxon test (a special case of PO model) has
> efficiency of 3/pi compared to the t-test if normality holds.
>
> Other approaches: Cox PH model, avas, ace.  My book covers these too.

Thanks, Frank, for the useful information.

Paul