[R] Chi-squared approximation may be incorrect

[Meyners, Michael, LAUSANNE, AppliedMathematics]

Nancy (?),
see ?chisq.test (in particular the examples and the comment on "expected
frequency" there). 
A rule of thumb (see any basic text book) for the chisquared
approximation being okay is that the expected value in each cell is at
least 5. The warning tells you that this does not hold true for at least
one of your cells. 
You might want to try 
chisq.test(t, simulate.p.value = TRUE) 
instead.
Michael

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On Behalf Of SNN
Sent: Mittwoch, 12. August 2009 00:34
To: r-help at r-project.org
Subject: [R] Chi-squared approximation may be incorrect



Hi,


I am trying to run a Chi squre test but I am getting the following
message

Warning messages:
1: In chisq.test(t) : Chi-squared approximation may be incorrect

Does anyone what it means?

your help is appreciated


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