[R] error message

[Uwe Ligges]

On Sat, 24 Jan 2004, forkusam wrote:

> 
>  I am trying to calculate n, using power.t.test
> 
> power.t.test(n=NULL,delta=delta, sd=sigmaEins,
> sig.level= alpha, power=power, type=c("two.sample"),
> alternative=c("two.sided"))
> 
> The values of the parameter are read in from a file.
>  I have no idea what the error message means.

Peter Dalgaard asked you to specify a *reproducible* example.
So, please specify some values for delta, sigmaEins, alpha, power.

Uwe Ligges

 
> --- Peter Dalgaard <p.dalgaard at biostat.ku.dk> wrote:
> > forkusam <forkusam at yahoo.com> writes:
> > 
> > >  Hi,
> > > Can someone please tell me what such an error
> > message
> > > could mean. i.e where a problem must have arised.
> > > 
> > > Error in uniroot(function(n) eval(p.body) - power,
> > > c(2, 1e+07)) : 
> > >         f() values at end points not of opposite
> > sign
> > 
> > Looks like the innards of one of the power
> > calculations, finding n to
> > achieve a given power. You'd likely get an error
> > like that if the
> > power is not between 0 and 1, but how about telling
> > us what you were
> > trying to do?
> > 
> > -- 
> >    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
> 
> 
> =====
> =====================
> Sylvie B. Forkusam
> Eppelheimer Str.52/A2-5-2
> 69115 Heidelberg, Germany
> Tel: (0049)-06221/346913
> Mobile: 0179-6816276
> 
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