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. With thanks, Ted. -------------------------------------------------------------------- E-Mail: (Ted Harding) <Ted.Harding at nessie.mcc.ac.uk> Fax-to-email: +44 (0)870 094 0861 Date: 26-Apr-05 Time: 15:02:24 ------------------------------ XFMail ------------------------------
Finding 'ncp' for t
3 messages · (Ted Harding), Peter Dalgaard
(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
On 26-Apr-05 Peter Dalgaard wrote:
(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...
Thanks for reminding me of this, Peter. It can be persuaded to do what I want! Also to Rolf Turner for his suggestion. Best wishes, Ted. -------------------------------------------------------------------- E-Mail: (Ted Harding) <Ted.Harding at nessie.mcc.ac.uk> Fax-to-email: +44 (0)870 094 0861 Date: 26-Apr-05 Time: 20:13:16 ------------------------------ XFMail ------------------------------