normality test

----- Original Message -----
From: "Romain Francois" <francoisromain at free.fr>
To: "Pieter Provoost" <pieterprovoost at gmail.com>; "RHELP"
<R-help at stat.math.ethz.ch>
Sent: Thursday, April 28, 2005 2:03 PM
Subject: Re: [R] normality test

Le 28.04.2005 13:16, Pieter Provoost a ??crit :

Hi,

I have a small set of data on which I have tried some normality tests.

When I make a histogram of the data the distribution doesn't seem to be
normal at all (rather lognormal), but still no matter what test I use
(Shapiro, Anderson-Darling,...) it returns a very small p value (which as
far as I know means that the distribution is normal).

Am I doing something wrong here?
Thanks
Pieter

Hello,

You seem to know not far enougth.
Null hypothesis in shapiro.test is **normality**, if your p-value is
very small, then the data is **not** normal.

Look carefully at ?shapiro.test and try again. Furthermore, normality
tests are not very powerful. Consider using a ?qqnorm and ?qqline

Romain

Thanks, I thought null hypothesis for these tests was "no normality"...

Pieter