Bill Simpson <[EMAIL PROTECTED]> writes: > I have continuous variables x, y, z. The plot of the data looks like this: > > y > | z=1(o), 2(@), 3(#), 4(*) > | > |* * * > | > | > |# # # # > | > | > |@ @ @ @ > | > | o > | o > | o > | o > |o > ------------------------ x > The correct model appears to be: if z==1, y~x+z; else y~z > (y~z + z:x isn't it)
Not if z really is continuous... > How can I express this model in lm()? If I can't express it properly in > lm(), what is the best way to fit the model? I'd try something like x2 <- ifelse(z==1, x, 0) z2 <- factor(z) y ~ x2+z2 -- O__ ---- Peter Dalgaard Blegdamsvej 3 c/ /'_ --- Dept. of Biostatistics 2200 Cph. N (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 ~~~~~~~~~~ - ([EMAIL PROTECTED]) FAX: (+45) 35327907 ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
