p.dalgaard at biostat.ku.dk
Thu Dec 9 18:56:32 CET 2004
m p <mzp3769 at yahoo.com> writes:
> I am looking into description of surf.ls(spatial)
> and see under value $beta - the coefficients.
> When I use polynomial of degree 2 to fit surface
> I expect to get 4 coefficients:
> z = a_1 x^2 + a_2 xy + a_3 y^2 + a_4
> What do beta really stand for and why do I get
> $beta vector of length 6?
Why do you expect a constant term but no linear terms? I'm too lazy to
verify, but it sounds like that would be your missing 2 coefficients.
O__ ---- Peter Dalgaard Blegdamsvej 3
c/ /'_ --- Dept. of Biostatistics 2200 Cph. N
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk) FAX: (+45) 35327907
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