You cannot have columns which are linearly dependent.
Starting a project which uses statistics without having some sort of
local statistical backup seems unprofitable.
install.packages("fortunes") # if not already done
library(fortunes)
fortune(122)
On 02/04/2015 15:20, Fix Ace wrote:
Thank you very much for the response. Then what does it mean? I am not a
stat person, but have to use it for my project. :(
Could you please recommend some readings about it? Thanks a lot!
On Wednesday, April 1, 2015 10:58 AM, Michael Dewey
<li...@dewey.myzen.co.uk> wrote:
This is really a question about statistics rather than R but see below
On 01/04/2015 06:28, Fix Ace wrote:
> I tried to run the sample code from R:
> dd <- data.frame(a = gl(3,4), b = gl(4,1,12)) a b
> 1 1 1
> 2 1 2
> 3 1 3
> 4 1 4
> 5 2 1
> 6 2 2
> 7 2 3
> 8 2 4
> 9 3 1
> 10 3 2
> 11 3 3
> 12 3 4
> options("contrasts")
> model.matrix(~ a + b, dd)(Intercept) a2 a3 b2 b3 b4
> 1 1 0 0 0 0 0
> 2 1 0 0 1 0 0
> 3 1 0 0 0 1 0
> 4 1 0 0 0 0 1
> 5 1 1 0 0 0 0
> 6 1 1 0 1 0 0
> 7 1 1 0 0 1 0
> 8 1 1 0 0 0 1
> 9 1 0 1 0 0 0
> 10 1 0 1 1 0 0
> 11 1 0 1 0 1 0
> 12 1 0 1 0 0 1
> when I tried to remove the intercept from the matrix, I used the
following codemodel.matrix(~ 0+a + b, dd)
> a1 a2 a3 b2 b3 b41 1 0 0 0 0 02 1 0 0 1 0 03 1 0 0 0 1 04 1 0 0 0 0
15 0 1 0 0 0 06 0 1 0 1 0 07 0 1 0 0 1 08 0 1 0 0 0 19 0 0 1 0 0 010 0
0 1 1 0 011 0 0 1 0 1 012 0 0 1 0 0 1 when I tried to remove the intercept
>
That got mangled but
In your matrix below try forming the sum of a1+a2+a3 and the sum of
b1+b2+b3+b4. I think you will find they are linearly related.
> Here I noticed that, all levels of a, a1, a2, and a3, were included.
I wonder how I can include the "b1" in the matrix as well? a1 a2 a3 b1
b2 b3 b4
> 1 1 0 0 1 0 0 0
> 2 1 0 0 0 1 0 0
> 3 1 0 0 0 0 1 0
> 4 1 0 0 0 0 0 1
> 5 0 1 0 1 0 0 0
> 6 0 1 0 0 1 0 0
> 7 0 1 0 0 0 1 0
> 8 0 1 0 0 0 0 1
> 9 0 0 1 1 0 0 0
> 10 0 0 1 0 1 0 0
> 11 0 0 1 0 0 1 0
> 12 0 0 1 0 0 0 1
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help@r-project.org <mailto:R-help@r-project.org> mailing list -- To
UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
<http://www.r-project.org/posting-guide.html>
> and provide commented, minimal, self-contained, reproducible code.
>
--
Michael
http://www.dewey.myzen.co.uk/home.html
--
Michael
http://www.dewey.myzen.co.uk/home.html
______________________________________________
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
