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

[Gavin Simpson]

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.

G

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