michael_karsh at earthlink.net
2009-Oct-18 18:30 UTC
[Rd] Use of lm on polynomial models (PR#14014)
Full_Name: Michael Aaron Karsh Version: 2.8.0. OS: Windows XP Submission from: (NULL) (75.61.102.255) When I try lm(w ~ h^3 + h^2 + h) for example, it only gives coefficients for the intercept and for h. It does not give coefficients for h^2 or h^3.
RTFM time: h^3 is not the cube of h in an R formula (for that you need I(h^3)). See ?formula, for example. Simpler would be lm(w ~ poly(h, 3, raw=TRUE)) On Sun, 18 Oct 2009, michael_karsh at earthlink.net wrote:> Full_Name: Michael Aaron Karsh > Version: 2.8.0. > OS: Windows XP > Submission from: (NULL) (75.61.102.255) > > > When I try lm(w ~ h^3 + h^2 + h) for example, it only gives > coefficients for the intercept and for h. It does not give > coefficients for h^2 or h^3.So it is behaving correctly. -- Brian D. Ripley, ripley at stats.ox.ac.uk Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595
Others beware: this address does not accept replies, in defiance of the posting guide. On Mon, 19 Oct 2009, Prof Brian Ripley wrote:> RTFM time: h^3 is not the cube of h in an R formula (for that you need > I(h^3)). See ?formula, for example. > > Simpler would be lm(w ~ poly(h, 3, raw=TRUE)) > > > On Sun, 18 Oct 2009, michael_karsh at earthlink.net wrote: > >> Full_Name: Michael Aaron Karsh >> Version: 2.8.0. >> OS: Windows XP >> Submission from: (NULL) (75.61.102.255) >> >> >> When I try lm(w ~ h^3 + h^2 + h) for example, it only gives coefficients >> for the intercept and for h. It does not give coefficients for h^2 or h^3. > > So it is behaving correctly. > > > -- > Brian D. Ripley, ripley at stats.ox.ac.uk > Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ > University of Oxford, Tel: +44 1865 272861 (self) > 1 South Parks Road, +44 1865 272866 (PA) > Oxford OX1 3TG, UK Fax: +44 1865 272595 > > ______________________________________________ > R-devel at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel >-- Brian D. Ripley, ripley at stats.ox.ac.uk Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595