[R] forward model selection

[Stefano]

Dear all,

I want to select a linear model by means of a forward selection procedure, adding only the main terms, that is x1+x2+x3+...xn.
Is there a fast way to specify all the main terms without  writing each one?

For example:

linear <- step(lm(resp~1,data=dati),scope=(upper="all main effects",lower=~1),direction="forward")


Thanks,

Stefano


*******************************
Stefano Calza
Istituto di Statistica Medica e Biometria
Università degli Studi di Milano
Via G. Venezian, 1
20133 Milano

tel. +39 02/2361302, 02/70600908
fax 02/2362930

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