[R] Letter-based representation of pairwise comparisons
retama
retama1745 at gmail.com
Tue Oct 6 16:33:11 CEST 2009
Hello:
That's because the required input should be a symmetric matrix with all the
comparisons, e.g., it should have the self-comparisons diagonal. In an
hypotetical case with two treatments, the pairwise-comparison test output is
something like that:
A B
B 0.80 -
but multcompView requires an input like that one:
A B
A 1 -
B 0.80 1
That means you should add a new row and column for your missing treatments
and, then, a diagonal of "1"s meaning that each treatment compared with
itself will result in a p-value of 1 (maximal identity). Then, the new
matrix could be piped succesfully.
Regards,
Retama
goz wrote:
>
> hello,
>
> i try to use the multcomp letters, but i have problems with my results :
>
> here is my pvalue matrix (from a pairwise.t.test) :
>
> pair=pairwise.t.test(...)
> pair$p.value
>
> 0 B BxS
> B 0.01727 - -
> BxS 0.00013 0.00226 -
> S 0.87555 0.02610 0.00027
>
>
> i was thiking to have something like that :
> 0 B S BxS
> a b a c
>
> but function return :
>
>> multcompLetters(pair$p.value)
> B BxS S
> "a" "b" "a"
>
>
> first question : why the 0 traitement doesn't appears in result ?
> second : why the results differs than what i expected ?
>
> many thanks.
>
>
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