[R] R-squared for MARS models

[Gavin Simpson]

On Wed, 2006-04-19 at 21:18 +0200, Marco Girardello wrote:
> Hi,
> 
> is there an R function which can compute the R-squared
> for a mars model fitted using the mda package?
> 
> many thanks in advance
> 
> best regards
> 
> Marco Girardello

Julian Faraway's "Extending the Linear Model with R" Chapman & Hall/CRC
(page 248)has a small section on MARS and compares the MARS fit with
other methods by using the MARS basis functions in a linear model to get
an R^2:

# page 248 example
library(faraway)
library(mda)
data(ozone)
a <- mars(ozone[,-1], ozone[,])
(a.summ <- summary(lm(ozone[,1] ~ a$x-1)))
a.summ$r.squared

HTH

G
-- 
%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%
 *Note new Address and Fax and Telephone numbers from 10th April 2006*
%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%
Gavin Simpson                     [t] +44 (0)20 7679 0522
ECRC                              [f] +44 (0)20 7679 0565
UCL Department of Geography
Pearson Building                  [e] gavin.simpsonATNOSPAMucl.ac.uk
Gower Street
London, UK                        [w] http://www.ucl.ac.uk/~ucfagls/cv/
WC1E 6BT                          [w] http://www.ucl.ac.uk/~ucfagls/
%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%