[R] Non-linear "linear" models?

From: <eph1v3t8-rhls6783_at_mailblocks.com>
Date: Sun 24 Jul 2005 - 00:23:50 EST


Hi,

    I'm new to R (though I have spent hours trying to learn how to use it) and also not very knowledgeable
about statistics, so I hope you will excuse what may seem like a very basic question. I'm trying to use
R to do an ANOVA analysis for some data with an unbalanced design, and while I was trying to figure that out, I got confused about the purpose of the "lm". All definitions I can find of "linear model" are of the form:
y = a + b * x + e

  In other words, y is only linear in the dependent variable(s) x. However, the lm model seems to support higher order polynomials, e.g.:

> lm(dist ~ speed + I(speed^2)+I(speed^3), cars)

  Is there some sense in which that model is "linear", or is R's lm() providing extra functionality?

Thanks,
--Paul



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