lm: how to calculate rsquared of the predicted values?

1.  can I measure de R-squared value between the predicted(by the model) and
real (observed) values.?
2. Measure the RMSE error .

There is a function in the caret package called postResample that will
do that (even if you aren't using resampling).

As has been previously noted on this list, there are a number of
formulas for R-squared. This function uses the square of the
correlation between the observed and predicted. The next version of
caret will offer a choice of formulas.

Max

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Did you try to install using install.packages()?

install.packages("caret")

Warning in install.packages("caret") :
  argument 'lib' is missing: using '/scratch5/hb/R/R_LIBS/linux/library/'

trying URL 'http://cran.cnr.Berkeley.edu/src/contrib/caret_3.08.tar.gz'
Content type 'application/x-gzip' length 1428629 bytes (1.4 Mb)
opened URL
==================================================
downloaded 1.4 Mb

/server/scratch5/hb/R/R_LIBS/linux/library
* Installing *source* package 'caret' ...
** libs
gcc -std=gnu99 -I/usr/local/linux/R-2.6.1/include
-I/usr/local/linux/R-2.6.1/include  -I/usr/local/include    -fpic  -g
-O2 -c caret.c -o caret.o
gcc -std=gnu99 -shared -L/usr/local/lib64 -o caret.so caret.o
-L/usr/local/linux/R-2.6.1/lib -lR
** R
** data
** inst
** preparing package for lazy loading
Loading required package: lattice
** help
 >>> Building/Updating help pages for package 'caret'
     Formats: text html latex example

  BloodBrain                        text    html    latex
  applyProcessing                   text    html    latex   example
[snip]

The downloaded packages are in
        /tmp/Rtmpwxs3CH/downloaded_packages

library(caret)

Loading required package: lattice

/Henrik

Thank you Max Kuhn,

So I decided to install caret  (R version 2.6.0, gcc 4.1.2, caret 3.08,
slackware 12 and kernel 2.6.17.11), and I've got a problem:
R  CMD INSTALL caret
* Installing to library '/usr/local/lib/R/library'
* Installing *source* package 'caret' ...
** libs
//(it goes with no problem..)

//here comes the bug

** building package indices ...
Error in load(zfile, envir = envir) : error reading from connection
Calls: <Anonymous> ... .build_data_index -> list_data_in_pkg -> <Anonymous>
-> switch -> load
Execution halted
ERROR: installing package indices failed
** Removing '/usr/local/lib/R/library/caret'

Any ideas?
On Dec 8, 2007 3:38 PM, Max Kuhn <mxkuhn at gmail.com> wrote:

1.  can I measure de R-squared value between the predicted(by the model)

and

real (observed) values.?
2. Measure the RMSE error .

There is a function in the caret package called postResample that will
do that (even if you aren't using resampling).

As has been previously noted on this list, there are a number of
formulas for R-squared. This function uses the square of the
correlation between the observed and predicted. The next version of
caret will offer a choice of formulas.

--

Max

--
Best regards,

Giovane

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