On May 6, 2011, at 4:16 PM, Ben Haller wrote:
As for correlated coefficients: x, x^2, x^3 etc. would obviously be
highly correlated, for values close to zero.
Not just for x close to zero:
> cor( (10:20)^2, (10:20)^3 )
[1] 0.9961938
> cor( (100:200)^2, (100:200)^3 )
[1] 0.9966219
Is this what you mean, as a potential source of problems? Or if you
mean that the various other terms in my model might be correlated
with x, that is not the case; each independent variable is
completely uncorrelated with the others (this data comes from
simulations, so the independent variables for each data point were
in fact chosen by random drawing).
It didn't seem easy to post an example, since my dataset is so
large, but if either of you would be willing to look at this
further, I could upload my dataset to a web server somewhere and
post a link to it. In any case, thanks very much for your help;
I'll look into the things you mentioned.
Ben Haller
McGill University
http://biology.mcgill.ca/grad/ben/
David Winsemius, MD
West Hartford, CT
______________________________________________
R-help@r-project.org mailing list
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.
