[R] Power analysis for MANOVA?

[Charles C. Berry]

If you know what a 'general linear hypothesis test' is see

 	http://cran.r-project.org/src/contrib/Archive/hpower/hpower_0.1-0.tar.gz

HTH,

Chuck

On Mon, 26 Jan 2009, Adam D. I. Kramer wrote:

>
> On Mon, 26 Jan 2009, Stephan Kolassa wrote:
>
>>  My (and, judging from previous traffic on R-help about power analyses,
>>  also some other people's) preferred approach is to simply simulate an
>>  effect size you would like to detect a couple of thousand times, run your
>>  proposed analysis and look how often you get significance.  In your simple
>>  case, this should be quite easy.
>
> I actually don't have much experience running monte-carlo designs like
> this...so while I'd certainly prefer a bootstrapping method like this one,
> simulating the effect size given my constraints isn't something I've done
> before.
>
> The MANOVA procedure takes 5 dependent variables, and determines what
> combination of the variables best discriminates the two levels of my
> independent variable...then the discrimination rate is represented in the
> statistic (Pillai's V=.00019), which is then tested (F[5,18653] = 0.71).  So
> coming up with a set of constraints that would produce V=.00019 given my
> data set doesn't quite sound trivial...so I'll go for the "par" library
> reference mentioned earlier before I try this.  That said, if anyone can
> refer me to a tool that will help me out (or an instruction manual for RNG),
> I'd also be much obliged.
>
> Many thanks,
> Adam
>
>
>>
>>  HTH,
>>  Stephan
>> 
>>
>>  Adam D. I. Kramer schrieb:
>> >  Hello,
>> > 
>> >      I have searched and failed for a program or script or method to
>> >  conduct a power analysis for a MANOVA. My interest is a fairly simple 
>> >  case
>> >  of 5 dependent variables and a single two-level categorical predictor
>> >  (though the categories aren't balanced).
>> > 
>> >      If anybody happens to know of a script that will do this in R, I'd
>> >  love to know of it! Otherwise, I'll see about writing one myself.
>> > 
>> >      What I currently see is this, from help.search("power"):
>> > 
>> >  stats::power.anova.test
>> >                          Power calculations for balanced one-way
>> >                          analysis of variance tests
>> >  stats::power.prop.test
>> >                          Power calculations two sample test for
>> >                          proportions
>> >  stats::power.t.test     Power calculations for one and two sample t
>> >                          tests
>> > 
>> >      Any references on power in MANOVA would also be helpful, though of
>> >  course I will do my own lit search for them myself.
>> > 
>> >  Cordially,
>> >  Adam D. I. Kramer
>> > 
>> >  ______________________________________________
>> >  R-help at r-project.org mailing list
>> >  https://stat.ethz.ch/mailman/listinfo/r-help
>> >  PLEASE do read the posting guide 
>> >  http://www.R-project.org/posting-guide.html
>> >  and provide commented, minimal, self-contained, reproducible code.
>> > 
>> 
>> 
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
>

Charles C. Berry                            (858) 534-2098
                                             Dept of Family/Preventive Medicine
E mailto:cberry at tajo.ucsd.edu	            UC San Diego
http://famprevmed.ucsd.edu/faculty/cberry/  La Jolla, San Diego 92093-0901