Date:         Wed, 19 Nov 2008 09:07:49 +0100
Reply-To:     Marta García-Granero <mgarciagranero@gmail.com>
Sender:       "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
From:         Marta García-Granero <mgarciagranero@gmail.com>
Subject:      Re: Chi-sq statistics
In-Reply-To:  <9E13F34784A0461DA4EC611A3F99912F@caut.hku.hk>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Wincy Chan wrote:
> Thank you Marta, Johnny, and Gary for your reply. I obviously don't have the
> Exact Test module and am on way to order it.
>
A couple of clarifications I forgot to mention in my previous message:

- Chi-square tests can be valid even when expected frequencies are <5,
provided that:
1) the lowest expected frequency is not <1
2) the percentage of cells with frequencies<5 is lower than 20%

- If you need an exact p-value for a 2xk contingency table (not bigger),
there is a freeware utility (not surprisingly, its name is
EXACT2XK.EXE), part of the PEPI package. It used to be downloaded from
www.sagebrushpress.com, but unfortunately  it is not there anymore (the
domain is for sale, the page is full of worthless information now). I
think that the windows version of the package, WINPEPI, will do the
trick too. You can download WINPEPI from:
http://www.brixtonhealth.com/pepi4windows.html

HTH,
Marta García-Granero

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