Well at a minimum V4 and V6 (used in lm()) are not the same in these two 
data sets.  Not sure why but there it is.

Brian

Brian S. Cade

U. S. Geological Survey
Fort Collins Science Center
2150 Centre Ave., Bldg. C
Fort Collins, CO  80526-8818

email:  brian_cade@usgs.gov
tel:  970 226-9326



e-letter <inpost@gmail.com> 
Sent by: r-help-bounces@r-project.org
05/15/2008 03:37 PM

To
r-help@r-project.org
cc

Subject
Re: [R] Inconsistent linear model calculations






Below is direct copy from command terminals of both pcs (mandrake 92
with r 171; mandriva 2008 with r 251, respectively).

R : Copyright 2003, The R Development Core Team
Version 1.7.1  (2003-06-16)

R is free software and comes with ABSOLUTELY NO WARRANTY.
You are welcome to redistribute it under certain conditions.
Type `license()' or `licence()' for distribution details.

R is a collaborative project with many contributors.
Type `contributors()' for more information.

Type `demo()' for some demos, `help()' for on-line help, or
`help.start()' for a HTML browser interface to help.
Type `q()' to quit R.

> dubious<-read.table('/path/to/file/dodgy.csv')
> dubious

  V1  V2    V3    V4    V5       V6     V7
1  1 300 39.87 39.85 39.90 39.87333  90000
2  2 400 45.16 45.23 45.17 45.18667 160000
3  3 500 50.72 51.03 50.90 50.88333 250000
4  4 600 56.85 56.80 57.02 56.89000 360000
5  5 700 63.01 63.09 63.14 63.08000 490000
6  6 800 69.52 69.82 69.63 69.65667 640000
>
> lm(V6~V2+V7,data=dubious)

Call:
lm(formula = V6 ~ V2 + V7, data = dubious)

Coefficients:
(Intercept)           V2           V7
  2.553e+01    4.332e-02    1.480e-05

>

R version 2.5.1 (2007-06-27)
Copyright (C) 2007 The R Foundation for Statistical Computing
ISBN 3-900051-07-0

R is free software and comes with ABSOLUTELY NO WARRANTY.
You are welcome to redistribute it under certain conditions.
Type 'license()' or 'licence()' for distribution details.

  Natural language support but running in an English locale

R is a collaborative project with many contributors.
Type 'contributors()' for more information and
'citation()' on how to cite R or R packages in publications.

Type 'demo()' for some demos, 'help()' for on-line help, or
'help.start()' for an HTML browser interface to help.
Type 'q()' to quit R.

> dubious<-read.table('/path/to/file/dodgy.csv')
> dubious
  V1  V2    V3    V4    V5       V6     V7
1  1 300 39.87 39.85 39.90 39.87333  90000
2  2 400 45.16 45.23 45.17 45.18667 160000
3  3 500 50.72 51.03 50.90 50.88333 250000
4  4 600 56.85 56.80 57.02 56.89000 360000
5  5 700 63.01 63.09 63.14 63.08000 490000
6  6 800 69.52 59.68 69.63 66.27667 640000
> lm(V6~V2+V7,data=dubious)

Call:
lm(formula = V6 ~ V2 + V7, data = dubious)

Coefficients:
(Intercept)           V2           V7
  1.937e+01    7.168e-02   -1.537e-05

>

Below is the csv file itself:

1 300 39.87 39.85 39.90 39.87333  90000
2 400 45.16 45.23 45.17 45.18667 160000
3 500 50.72 51.03 50.90 50.88333 250000
4 600 56.85 56.80 57.02 56.89000 360000
5 700 63.01 63.09 63.14 63.08000 490000
6 800 69.52 59.68 69.63 66.27667 640000

Enjoy! :)

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