R help - Apr 2005 - normality test

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

-------------
par
0.07
0.05
0.04
0.04
0.011
0.063
0.043
0.073
0.099
0.11
0.0056
0.015
0.024
0.043
0.058
0.053
0.6
1.4
4.0
0.020
0.066
0.084
0.074
0.146
0.065
0.550
0.327
0.035
0.077
0.042
0.018
0.025

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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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