[R] How to search t value when you know degree of freedom?

[David L Carlson]

Perhaps a typo? It should be qt() not pt():

> pt(0.975, 29) 
[1] 0.8311882
> qt(0.975, 29) 
[1] 2.04523

-------------------------------------
David L Carlson
Department of Anthropology
Texas A&M University
College Station, TX 77840-4352



-----Original Message-----
From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Michael Dewey
Sent: Thursday, February 23, 2017 6:18 AM
To: vod vos <vodvos at zoho.com>; Rui Barradas <ruipbarradas at sapo.pt>
Cc: R-help at r-project.org
Subject: Re: [R] How to search t value when you know degree of freedom?

When I do pt(0.975, 29) I do not get 2.045 so I think you must have 
declared a new function pt which is interfering with things.

On 23/02/2017 10:40, vod vos wrote:
> If we want to get 95% limit of t value, the result will be
>
> pt(0.975, 29)  =  2.045
>
> is that right?
>
>
>  ---- On 星期三, 22 二月 2017 08:04:36 -0800 Rui Barradas <ruipbarradas at sapo.pt> wrote ----
>  > Hello,
>  >
>  > It would be ?pt not pnorm.
>  > And as you can see in that help page you need another value, the value
>  > of the quantile. (Don't worry about the arguments ncp or log just q and df)
>  >
>  > Hope this helps,
>  >
>  > Rui Barradas
>  >
>  > Em 22-02-2017 15:53, vod vos escreveu:
>  > >
>  > > Hi everyone,
>  > >
>  > > How to search t value when you know degree of freedom?
>  > >
>  > > For example, the degree of freedom is 29, how to use R to calculate the t value for it?
>  > >
>  > > t.test does not help, or pnorm? I am not sure.
>  > >
>  > > Thanks.
>  > >
>  > > ______________________________________________
>  > > R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
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>  > > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>  > > and provide commented, minimal, self-contained, reproducible code.
>  > >
>  >
>
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

-- 
Michael
http://www.dewey.myzen.co.uk/home.html

______________________________________________
R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.