[R] paired t-test vs pairwise t-test

[Rolf Turner]

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