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Bug? (PR#1710)

2 messages · Lauri.Mehtatalo@metla.fi, Brian Ripley

Original
Lauri.Mehtatalo@metla.fi
# 
Hi,

I tried to do a multiple linear model from the example 
dataset Formaldehyde. However, the function lm() did not 
estimate the coefficient of the term carb^2. The same 
problem occurred with the (nlme)dataset Pixel with both 
function lme() and lm(). I am using the windows version of 
R 1.5.1

Lauri Mehtatalo

The Formaldehyde example:
Call:
lm(formula = optden ~ carb + carb^2, data = 
Formaldehyde)

Coefficients:
(Intercept)         carb  
   0.005086     0.876286  

The Pixel example:
+ if(nchar(pkg)) library(pkg, character.only=TRUE)}
Loading required package: nls 
Loading required package: lattice
~day,Side=~1)))
     (Intercept)         day
1/L     1048.995  0.32564928
1/R     1043.659  0.32564928
10/L    1144.898 -0.63867455
10/R    1099.883 -0.63867455
2/L     1054.011  0.65786288
2/R     1048.726  0.65786288
3/L     1065.000  0.45552014
3/R     1075.759  0.45552014
4/L     1088.173  0.93300591
4/R     1088.854  0.93300591
5/L     1125.918 -0.91429707
5/R     1129.309 -0.91429707
6/L     1112.721 -0.72735611
6/R     1094.164 -0.72735611
7/L     1133.443 -1.69593549
7/R     1156.943 -1.69593549
8/L     1101.205  0.05435070
8/R     1087.689  0.05435070
9/L     1093.513  0.05987474
9/R     1071.482  0.05987474
(Intercept)         day 
1076.820678    1.341873  
- - - - - - - - - - - - -
Lauri Mehtätalo
Metsäntutkimuslaitos
Joensuun tutkimuskeskus
PL 68 (Yliopistokatu 7)
80101 JOENSUU
lauri.mehtatalo@metla.fi
p. 013-251 4110
- - - - - - - - - - - - -

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Brian Ripley
# 
This is NOT A BUG.

If you want a squared term, you need to include I(carb^2).  See ?formula
or even `An Introduction to R'.

Please

1) Use an informative subject line, as only the subject appears in the
BUGS summary file.

2) Read the Bugs section in the FAQ, and only post to R-bugs if you
are absolutely sure you understand.
On Wed, 26 Jun 2002 Lauri.Mehtatalo@metla.fi wrote: