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List:       r-help
Subject:    Re: [R] Fisher's Test 5x4 table
From:       paul brett <brettpaul16 () gmail ! com>
Date:       2015-08-31 14:54:02
Message-ID: CAE1X91ozFb=U59hnNtT50bjYZaEPowQ=WJZ0rrYkU5G8GeOwtg () mail ! gmail ! com
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Hi Peter and Gerrit,
                            Sorry about my confusion with the results I was
not entirely sure what they were. I was expecting some form of a table and
i didn't realize that with the results of a fisher test, one just gets a
p-value. I had tried the 'estimate' and 'null.value' which gave me a null
value which upon looking again I don't do but I know that now).
                            Thanks very much for the help, this has been my
5th different statistical package to try and do this test. So I suppose I
had a suspicous/this is too good to be true reaction to the result. I
wasn't entirely sure what it was. Thanks for clearing this up for me.

                            Thanks again,
                                                Paul

On Mon, Aug 31, 2015 at 9:00 AM, peter dalgaard <pdalgd@gmail.com> wrote:

>
> > On 30 Aug 2015, at 13:54 , paul brett <brettpaul16@gmail.com> wrote:
> >
> > Fisher's Exact Test for Count Data with simulated p-value (based on 1e+07
> > replicates)
> >
> > data:  Trapz
> > p-value = 1e-07
> > alternative hypothesis: two.sided
> >
> >
> > Dispite these chages, the changes equations is not giving me the results
> > for the calculations. The changes I have made seem to satisfy what is in
> > the details section on R, and I don't have the issue of workspace in R.
> > What I do to get the results of the fisher test?
> > Is there something simple that I am missing?
>
> The theory?
>
> There is nothing more to Fisher's test than the calculation of the
> probability of obtaining a table as or less (im-)probable as the one
> observed. This is the p-value. You have done 10 million simulations and not
> found a single table that is less likely than the one observed. Hence, the
> p-value is 1/10 000 001 = ca. 1e-7, counting in the observed table.
>
> --
> Peter Dalgaard, Professor,
> Center for Statistics, Copenhagen Business School
> Solbjerg Plads 3, 2000 Frederiksberg, Denmark
> Phone: (+45)38153501
> Email: pd.mes@cbs.dk  Priv: PDalgd@gmail.com
>
>
>
>
>
>
>
>
>

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