[R] Help with perm.test please

- - mbatobeme at yahoo.com
Thu Sep 5 14:09:24 CEST 2002


Sorry of this is a repeat-the original message didn't
seem to go through.....

I have two groups that I am trying to do a two sample
permutation test on (equality of means).

The x group has 6 elements and the y group has 703
elements. 

However, the data is counts and there are only a few
unique values:

> unique(x)
[1] 1 2
> unique(y)
 [1]  1  2  5  3 10  9  7  4  6 11  8 23 18 30 16 29
42

Now I understand that you don't need to be a
weatherman to see which way the wind is blowing here
and clearly you would reject the null of equality.

I thought that perm.test creates a rx2 contingency
table and then does a network algorithm ala stat exact
(or something like that). In this example it doesn't
seem that the contingency table would be that big. Any
suggestions or comments ?

Thanks,

Steve

But I get the following error:

> perm.test(x,y,exact=T)
Error in cperm(eq, m, paired) : N > 200 in cpermdistr2



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