you could try the following: f <- function(delta, pr, x, df) pt(x, df = df, ncp = delta) - pr out <- uniroot(f, c(0, 37.62), pr = 0.18, x = 0.9, df = 4) ##########3 out$root pt(0.9, 4, out$root)
I hope it helps. Best, Dimitris ---- Dimitris Rizopoulos Ph.D. Student Biostatistical Centre School of Public Health Catholic University of Leuven Address: Kapucijnenvoer 35, Leuven, Belgium Tel: +32/(0)16/336899 Fax: +32/(0)16/337015 Web: http://www.med.kuleuven.be/biostat/ http://www.student.kuleuven.be/~m0390867/dimitris.htm ----- Original Message ----- From: "Matthieu Dubois" <[EMAIL PROTECTED]> To: <r-help@stat.math.ethz.ch> Sent: Thursday, March 02, 2006 9:39 AM Subject: [R] finding ncp for t distribution > Dear R-users, > > > I am wondering whether R implements a function returning the non > central > parameter of a t distribution (equivalent of the TnoncT function > from > SAS), given /x/ a value from a t distribution, /df /the degrees of > freedom and /p/ the probability of x under this distribution. > > > Thanks a lot, > > > Matthieu > > > -- > > Matthieu Dubois, /Ph.D/. /Student/ > > Cognitive Neuroscience Unit, UCL, Belgium > > > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! > http://www.R-project.org/posting-guide.html > Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html