Re: [R] Does the t.test in R uses Welch procedure or ordinary student t-test?

From: Gavin Simpson <>
Date: Thu, 14 Feb 2008 11:01:06 +0000

On Thu, 2008-02-14 at 11:51 +0100, Kes Knave wrote:
> Dear all
> I have run t.test(), and get a output similar to this:
> t.test(extra ~ group, data = sleep)
> Welch Two Sample t-test


Pretty big hint don't you think?

> data: extra by group
> t = -1.8608, df = 17.776, p-value = 0.0794
> alternative hypothesis: true difference in means is not equal to 0
> 95 percent confidence interval:
> -3.3654832 0.2054832
> sample estimates:
> mean in group 1 mean in group 2
> 0.75 2.33
> Should this be refered as a Welch procedure or ordinary student t-test?
> Regards Kes

Please, Kes, read the help pages (written by volunteers giving of their own free time) instead of expecting others to do this for you.

?t.test tells you what you want to know. This isn't that difficult to find, is it? The posting guide asks you to do this before posting to the list. If for no other reason than saving yourself time waiting for replies, you should learn how to find out information for yourself in R, and the posting guide shows you how.


 Dr. Gavin Simpson             [t] +44 (0)20 7679 0522
 ECRC, UCL Geography,          [f] +44 (0)20 7679 0565
 Pearson Building,             [e]
 Gower Street, London          [w]
 UK. WC1E 6BT.                 [w]

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Received on Thu 14 Feb 2008 - 11:06:40 GMT

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