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Normal distribution test

On Tue, Nov 17, 2009 at 11:17 AM, Markus Mehrwald <mehrwald at ira.uka.de> wrote:
I suppose you want to say you have a sample of three-dim data, say
represented be vectors x1,x2,x3,
and your question is if this data (x1|_1,x2_1, x3_1),...,(x1_n,x2_n, x3_n)
are generated by a three-dim multinormal distribution. That is very
simple, a very good
test is to simply say "reject".  I have never seen three-dim data
which are truly
multinormal.  So a better question is to ask if amultinormal
distribution can be an acceptable
approximation, but then we need to know what is your purpose of
analysis! If you are interested in
extremes or extrere quantiles, then a normal approx is never safe.

If you want a statistical test, then a multivariate extension of
shapiro-wilk is in
install.packages("mvnormtest", dep=TRUE)
library(mvnormtest)
?mshapiro.test

kjetil