Re: When to use Fisher?

In article
<13316125.1120216924131.JavaMail.jakarta@xxxxxxxxxxxxxxxxxxxxxx>,
\Luis A. Afonso\ <licas_@xxxxxxxxxxx> wrote:
<Snip>
> In particular reporting to the numeric example posted by Tim:

> _______23_______8
> ________5_______2

> gives p = 0.6077. This tail does not allow us to reject H0. Then the >two groups are not different. (I love numbers; blah, blah, blah, not >too much).

> ___a11___a12___a21___a22_______________________
> ___23____8______5_____2________1)__0.3604
> ___24____7______4_____3________2)__0.1947
> ___25____6______3_____4________3)__0.0545
> ___26____5______2_____5________4)__0.0075
> ___27____4______1_____6________5)__0.0005
> ___28____3______0_____7________6)__0.0000

> _____________Tail´s size______________0.6077

Sorry to be so dumb, but I don't understand this.

I thought that the smallest frequency should be decremented, so that
the table would be calculated with a22 going from 2 to 1 to 0. For me
this gives:-

Fisher's Exact Test for Var 4

Possible frequency
distributions

23 8
5 2 Probability 0.350437

22 9
6 1 Probability 0.29852

21 10
7 0 Probability 0.0938206

Total probability of distributions at least as extreme = 0.742777

Is this utter nonsense?

Robin


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