[R] paired t-test vs pairwise t-test
Rolf Turner
rolf at math.unb.ca
Thu Aug 19 18:42:21 CEST 2004
You wrote:
> What's the difference between t.test(x, y) and pairwise.t.test()? Is
> it just that the former takes two vectors, whereas the latter takes a
> vector and a factor?
No. The pairwise.t.test() function (according to the help
file) does a multiplicity of t-tests, on more than two
samples, adjusting the p-value to compensate for the
multiplicity by various methods.
IMHO the name of this function is bad, because to me it
suggests doing ***paired*** t-tests, which would trip up the
naive user, who probably wouldn't notice or would ignore the
"t tests with pooled SD" message in the output. As one of
the Ripley fortunes says ``It really is hard to anticipate
just how silly users can be.'' But why go out of the way to
give them a chance to be silly?
cheers,
Rolf Turner
rolf at math.unb.ca
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