I have collected some code snippets I used recently for working with polynomials. The idea of writing this page came from a question I was asked a few days ago by Titta Kotilainen. I should emphasize that the page linked below concerns only polynomials, and excludes all other linear models that can be fit with
lm(). Even models that are polynomials but formulated not as a regular polynomial equation (e.g.
x ~ I(x^2) + x instead of the expected
x + I(x^2) will quietly fail! In contrast, use of
poly() as in
y ~ poly(x, 2) is fine.