[R] Model II regression on segmented data
plorch at zoo.utoronto.ca
Fri Oct 4 05:35:46 CEST 2002
I am interested in doing Reduced Major Axis regression in R. Has anyone
I am aware of how to calculate the slope using RMA (and previous threads
on this list about RMA), but I would like to estimate break points in
data where there are two (or more) distinct trends. This is
straightforward with Ordinary Least Squares (iteratively try x values,
set up dummy variables, find x that maximizes R^2). But it seems like
it would be more difficult with RMA. The critical thing, it seems to
me, would be how to estimate R^2 for the more complex model. Once the
break point is identified, it would also be nice to also estimate the
two (or more trends).
Thanks for any help you can give.
Dr. Patrick D. Lorch
Zoology Dept. W: 416-978-0172
University of Toronto F: 416-978-8532
Ramsay Wright Labs plorch at zoo.utoronto.ca
25 Harbord St. http://www.zoo.utoronto.ca/lrowe/plorch
Toronto, Ontario M5S 3G5
Public encryption key available upon request.
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