-----Original Message----- From: Robert.Denham at dnr.qld.gov.au
[mailto:Robert.Denham at dnr.qld.gov.au]
Sent: Monday, 9 July 2001 5:20 PM To: r-help at hypatia.math.ethz.ch Subject: [R] polynomial regression and poly When doing polynomial regression I believe it is a good idea to use the
poly
function to generate orthogonal polynomials. When doing this in Splus
there
is a handy function (transform.poly I think) to convert the coefficients produced by regression with the poly function back to the original scale. Has somebody written something similar for R ? Robert
Couple of fastidious little points. If there is such a thing in S-PLUS, I am not aware of it. What is available is the ability to evaluate the same polynomials at different x-values. (See, for examle, poly.raw .) Also it is not completely clear what you mean by "back to the original scale". I presume this means "back to the standard power basis". The only facility I am aware of that will do this is the polynom library, but can be a considerable investment in time to learn how to use it. There is a fairly good payoff, though, if you are going to be fiddling with univariate polynomials like this at all often. Bill Venables -- Bill Venables, CMIS CSIRO Marine Laboratories, PO Box 120, Cleveland, Qld. 4163 Phone: +61 7 3826 7251 Fax: +61 7 3826 7304 Email: Bill.Venables at cmis.csiro.au http://www.cmis.csiro.au/bill.venables/ -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._