[R] Is there t.test with null hypothesis?

[Matti Viljamaa]

> On 08 Sep 2016, at 15:48, Michael Dewey <lists at dewey.myzen.co.uk> wrote:
> 
> Dear Matti
> 
> On 08/09/2016 13:06, Matti Viljamaa wrote:
>> I’m trying to do a t-test, where the null hypothesis for the two data sets has to be:
>> 
>> “the means are the same”/“difference in means is equal to one”
>> 
> 
> That is two statements not one. Do you mean that your null is that the difference is 1? If so just subtract 1 from all the scores in the group which is predicted to be higher and run the t-test on the resulting scores.

Sorry typo, should of course be:

“the means are the same”/“difference in means is equal to zero”

so they are synonymous.

>> Using the t.test function in R I’m able to see that it uses the following “alternative hypothesis”:
>> 
>> alternative hypothesis: true difference in means is not equal to 0
> 
> It means that the null is that the difference is zero.
> 
>> 
>> but does not seem to specify null hypothesis. I believe alternative and null hypotheses are different, although
>> I don’t exactly know how.
>> 
>> So what should I use for my t-test? Or is t.test ok?
>> 
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> 
> -- 
> Michael
> http://www.dewey.myzen.co.uk/home.html