[R] Specify model with polynomial interaction terms up to degree n
David Winsemius
dwinsemius at comcast.net
Mon Jul 2 16:51:28 CEST 2012
On Jul 2, 2012, at 9:29 AM, YTP wrote:
> I would like to specify a model with all polynomial interaction
> terms between
> two variables, say, up to degree 6. For example, terms like a^6 +
> (a^5 *
> b^1) + (a^4 * b^2) + ... and so on. The documentation states
>
> The ^ operator indicates crossing to the specified degree.
>
> so I would expect a model specified as y ~ (a+b)^6 to produce these
> terms.
> However doing this only returns four slope coefficients, for
> Intercept, a,
> b, and a:b. Does anyone know how to produce the desired result?
> Thanks in
> advance.
You might try:
poly(a,6)*poly(b,6)
(untested ... and it looks somewhat dangerous to me.)
--
David Winsemius, MD
West Hartford, CT
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