[R] normality test

[Romain Francois]

Le 28.04.2005 13:16, Pieter Provoost a écrit :

>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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