[R] Understanding lm-based analysis of fractional factorial experiments

[Ben Bolker]

Kjetil Kjernsmo <kjekje <at> ifi.uio.no> writes:

> 
> All,
> 
> I have just returned to R after a decade of absence, and it is good to 
> see that R has become such a great success! I'm trying to bring Design 
> of Experiments into some aspects of software performance evaluation, and 
> to teach myself that, I picked up "Experiments: Planning, Analysis and 
> Optimization" by Wu and Hamada. I try to reproduce an analysis in the 
> book using lm, but have to conclude I don't understand what lm does in 
> this context, even though I end up at the desired result. I'm currently 
> using R 2.15.2 on a recent Fedora system, but I get the same result on 
> Debian Wheezy and Debian Squeeze. I think the discussion below can be 
> followed without having the book at hand though.

   Just a quick thought (sorry for removing context): what happens if
you use sum-to-zero contrasts throughout, i.e. options(contrasts=c("contr.sum",
"contr.poly")) ... ?