[R] help about: anova and population no normal

[Mike Lawrence]

Oh, and to answer your question more directly, the randomization test
permits testing hypotheses using any metric, so scale & shape are
definitely testable.

Typically one is interested in means, so on each iteration of the test
loop one computes the group/condition means. However, it's simple to
instead compute, say, the best fit weibull to each condition and
simultaneously test shift, shape, and scale.



On Tue, Mar 31, 2009 at 12:18 PM, Mike Lawrence <Mike.Lawrence at dal.ca> wrote:
> Those with more formal statistical backgrounds may provide better
> advice, but in my own informal training I've come to wonder why
> parametric stats persist in the face of modern computing power. As I
> understand it, Fisher developed ANOVA as low-computation method of
> approximating the Randomization Test (a.k.a. exhaustive permutation
> test). Where computation power has grown exponentially since Fisher's
> time, these days it is feasible to compute the full R-Test in many
> cases, and for those cases where the full R-Test  is not feasible,
> non-exhaustive permutation variants usually satisfy. Indeed, it has
> been shown (http://brm.psychonomic-journals.org/content/37/3/426.short)
> that the R-Test is more powerful than the F-Test in the face of skewed
> distributions.
>
> My advice would thus be to abandon parametrics and simply code a
> randomization test variant of the ANOVA you want.
>
> Mike
>
> On Tue, Mar 31, 2009 at 10:29 AM, Sarti Maurizio <sarti.m at irea.cnr.it> wrote:
>> Dear R-Helpers,
>>
>> Parametric statistics are statistics where the population is assumed to fit any
>> parametrized distributions (most typically the normal distribution).
>> My problem is:
>> 1) if my polulation is no normal
>> 2) if the sample data of all replications and treatments were well fitted from
>> the Weibull distribution (shape and scale parameters).
>>
>> Can be The shape and scale parameters compared between treatments by using the
>> canonical analysis of the variance ANOVA?
>>
>> Many thanks for your help with these questions.
>>
>> Maurizio
>>
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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.
>>
>
>
>
> --
> Mike Lawrence
> Graduate Student
> Department of Psychology
> Dalhousie University
>
> Looking to arrange a meeting? Check my public calendar:
> http://tinyurl.com/mikes-public-calendar
>
> ~ Certainty is folly... I think. ~
>



-- 
Mike Lawrence
Graduate Student
Department of Psychology
Dalhousie University

Looking to arrange a meeting? Check my public calendar:
http://tinyurl.com/mikes-public-calendar

~ Certainty is folly... I think. ~