R help - Nov 2003 - adding variable

Hello, 

I have count data of animals (here y, y1, y2...) and env. variables (x, x1, 
x2 ,....).

I used a glm 

glm(y~x1+x2+x3....)

glm(y1~x1+x2+x3....)

and now I would like to add the count data of other species to investigate if 
they might have a bigger impact than the env. variables:

#x? are the selected var from the first glm run

glm(y~x?+x?+y1)

glm(y~x?+x?+x?+y2)

....

I wonder if there is a more elegant method to do this than adding (and 
removing) each y by hand. 

thanks in advance, cheers Martin

On Tue, 18 Nov 2003, Martin Wegmann wrote:
> I have count data of animals (here y, y1, y2...) and env. variables (x, x1,
> x2 ,....).
> 
> I used a glm 
> 
> glm(y~x1+x2+x3....)
> 
> glm(y1~x1+x2+x3....)
> 
> and now I would like to add the count data of other species to investigate
if
> they might have a bigger impact than the env. variables:
> 
> #x? are the selected var from the first glm run
> 
> glm(y~x?+x?+y1)
> 
> glm(y~x?+x?+x?+y2)
> 
> ....
> 
> I wonder if there is a more elegant method to do this than adding (and 
> removing) each y by hand. 
Do you mean each x?  In either case, see ?update.

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595