Werner,
You could set 0 to that regressors you don't want to consider for
prediction.
da <- expand.grid(A=1:20, B=rnorm(20, 4, 0.2), C=10^seq(1,2,l=20))
da$y <- rnorm(da$A, 0, 0.3)
m0 <- lm(y~A+B+C, data=da)
new <- da
new$C <- 0
predict(m0)[1:5]
predict(m0, newdata=new)[1:5]
At your disposal.
Walmes.
-----
..oooO
..................................................................................................
..(....)... 0ooo... Walmes Zeviani
...\..(.....(.....)... Master in Statistics and Agricultural
Experimentation
....\_)..... )../.... walmeszeviani at hotmail.com, Lavras - MG, Brasil
............
(_/............................................................................................