[R] qt with ncp?

Peter Malewski peter.malewski at gmx.de
Mon May 7 18:53:12 CEST 2001


On Mon, May 07, 2001 at 06:45:32PM +0200, Peter Dalgaard BSA wrote:
> Peter Malewski <peter.malewski at gmx.de> writes:
> 
> > Does anybody has a function or idea how to calculate qt with a noncentrality 
> > parameter? I'm porting a SAS-macro for equivalence (Wellek, 1994 TT2ST) to R 
> > and it seems that I need this to calculate tinv (SAS-command, I hope that 
> > this is R's qt,...I get the SAS-macro manual next week).
> 
> The easiest way is probably to use something like
> 
> uniroot(function(x)pt(x, df, ncp) - p, c(-1e7,1e7))
> 
> It's not going to be fast, but if you just need one of them...
> 
> (Look inside power.t.test for variations on the theme)

Thanks for that hint. I'll see.
Peter

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