[R] Independant-samples t-test

Mark Myatt mark at myatt.demon.co.uk
Mon Apr 2 11:27:50 CEST 2001

Dr Stuart Leask <stuart.leask at nottingham.ac.uk> writes:
>I can't find a 'group' option in t.test (library ctest).
>(eg. X = normally-distributed rating scale
>Y = sex
>I'd like to compare the means by sex, but can't do t.test(X,group=Y) or

Index the vector by group:

        t.test(x[sex == 1], x[sex == 2])

should do the trick. You could try:


which is equivalent but assumes equal variances.


Mark Myatt

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