[R] ANOVA-like tests of geometrically-distributed data

[vito muggeo]

Hi Robert,
if you are not a statistician and you have a statistical problem, please
consult a statistician (or someone familiar with Statistics)!

I think that the different professions (statistician, medical doctors,....)
are very useful to improve everything (including joint works/papers)

In my opinion, availability of PC with free statistical softwares (e.g. R)
are not sufficient to understand the Statistics and to perform and to solve
(correctly) statistical problems.

Your words "I have also been told that something called a "generalized
linear model" " are well-self-explain, I believe.

regards,
vito



----- Original Message -----
From: "Robert Merkel" <rmerkel at venus.it.swin.edu.au>
To: <r-help at stat.math.ethz.ch>
Sent: Tuesday, July 16, 2002 8:04 AM
Subject: [R] ANOVA-like tests of geometrically-distributed data


> I have a statistical problem which has given me no end of grief recently,
> and am posting here in the hope that somebody can give me a straight
> answer.  I'm a IT postgrad, not a statistician, so people may have to
> speak really slowly and clearly for me to get it :)
>
> I am collecting simulation data, and the results are geometrically
> distributed (or approximately so).  From what I can gather from my stats
> books, provided the sample size is large enough (>30 or so) I can use t
> and z-tests to compare means under different experimental conditions as
> the CLT says that the sample means will be approximately normally
> distributed.
>
> However, also as I understand it, the ANOVA explicitly assumes that the
> population is normally distributed, which is an assumption that in my case
> is not satisfied.
>
> I have also been told that something called a "generalized linear model"
> can be used to perform ANOVA-like statistics on geometrically-distributed
> data, but not how.
>
> There is R documentation on a function "glm" and also "anova.glm" which
> discuss stuff that looks vaguely like what I want to do, but I can't
> really make sense of it.
>
> Can these functions do what I'm trying to do?  If so, what's the
> procedure?
>
> Any help will be *much* appreciated.
>
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