lm coefficients
Do read ?poly: you have orthogonal polynomials.
On Tue, 3 Feb 2004, Timur Elzhov wrote:
Dear R experts, Excuse me if my question will be stupid... I'd like to fit data with x^2 polynomial: d <- read.table(file = "Oleg.dat", head = TRUE) d X T 3720.00 4.113 3715.00 4.123 3710.00 4.132 ... out <- lm(T ~ poly(X, 4), data = d)
You asked for 4 and got 2? Really?
out
Call:
lm(formula = T ~ poly(X, 2), data = d)
Coefficients:
(Intercept) poly(X, 2)1 poly(X, 2)2
9.803 -108.075 51.007
So, d$T best fitted with function
9.803 -108.075 * X + 51.007 * X^2,
yes?
No!
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