Message-ID: <4270D11B.7020902@free.fr>
Date: 2005-04-28T12:03:39Z
From: Romain Francois
Subject: normality test
In-Reply-To: <002f01c54be3$c307e0e0$1120780a@nioo.int>
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
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~~~~~~ Romain FRANCOIS - http://addictedtor.free.fr ~~~~~~
~~~~ Etudiant ISUP - CS3 - Industrie et Services ~~~~
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~~~~ Stagiaire INRIA Futurs - Equipe SELECT ~~~~
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