Message-ID: <x2mzrlsfwn.fsf@turmalin.kubism.ku.dk>
Date: 2005-04-26T15:42:48Z
From: Peter Dalgaard
Subject: Finding 'ncp' for t
In-Reply-To: <XFMail.050426160527.Ted.Harding@nessie.mcc.ac.uk>
(Ted Harding) <Ted.Harding at nessie.mcc.ac.uk> writes:
> Hi Folks,
>
> I'm looking for a neat procedure for the following:
>
> Given t0 such that
>
> pt(t0,df,ncp=0) = alpha (given)
>
> find ncp0 such that for given beta
>
> pt(t0,df,ncp=ncp0) = (1 - beta)
>
> (In other words, what's the ncp such that you get power (1-beta)
> to detect it, using a 1-sided test with size alpha when ncp = 0?)
>
> In the past I've done the groping by hand, but this time it
> needs to be done many times over, so a good solver for ncp0
> in this situation would be handy.
You might want to peek inside power.t.test(). Or just use it...
--
O__ ---- Peter Dalgaard Blegdamsvej 3
c/ /'_ --- Dept. of Biostatistics 2200 Cph. N
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk) FAX: (+45) 35327907