[R] how specify lme() with multiple within-subject factors?

[Bert Gunter]

Folks: 


Lme() is only able to work with nested random effects, not with crossed
random effects. 

Not quite true. Crossed models **can** be done, albeit clumsily, via
pdMatrix objects: the Bates/Pinheiro book even contains an example or two
(one on assay plates, I recall, but I don't have my book with me for the
reference). Also, lme, not lmer, is currently the only way to implement
penalized splines as random effects -- see the lmeSplines package.

-- Bert Gunter