Hi all,
I've been revising some lecture notes and I have something that used to
work with dummy.coef and now doesn't. A search of R help doesn't reveal
any recent discussion on this function, so I'd appreciate your thoughts.
The (compact/relevant) code is below, and complains at the line
rep.int(x1[[i]][1L], nl), levels = xl[[i]]) that the 'times' value is
invalid. This seems to relate to the the polynomial terms, but I'm not
sure how to take it further than that.
battery.df = data.frame(
voltage = c(130,155,74,180,34,40,80,75,20,70,82,
58,150,188,159,126,136,122,106,115,25,70,58,45,
138,110,168,160,174,130,150,139,96,104,82,60),
material = factor(rep(1:3,rep(12,3))),
temp = rep(rep(c(50,65,80),rep(4,3)),3))
battery.df = data.frame(voltage, material, temp)
battery.fit=lm(voltage~material*(temp+I(temp^2)),data = battery.df)
dummy.coef(battery.fit)
Error in rep.int(xl[[i]][1L], nl) : invalid 'times' value
Thanks,
James
--
James M. Curran, Ph.D.
Associate Professor
Director Bioinformatics Institute
Department of Statistics
Faculty of Science
Private Bag 92019
Auckland
New Zealand