Dear all,

I've read numerous posts about the random and nested factors in lme,
comparison to proc Mixed in SAS, and so on, but I'm still a bit confused by
the notations. More specifically, say we have a model with a fixed effect F,
a random effect R and another one N which is nested in R.

Say the model is described by Y~F
Can anyone clarify the difference between :
random = ~1|R:N
random = ~1|R/N
random = ~R:N
random = ~R/N
random = ~R|N
random = ~1|R+N

or direct me to an overview regarding notation of these formulas in lme
(package nlme)? The help files weren't exactly clear to me on this subject.

What confuses me most, is the use of the intercept in the random factor.
Does this mean the intercept is seen as random, has a random component or is
it just notation? In different mails from this list I found different
explanations.

Thank you in advance.
Cheers
Joris

-- 
Joris Meys
Statistical Consultant

Ghent University
Faculty of Bioscience Engineering
Department of Applied mathematics, biometrics and process control

Coupure Links 653
B-9000 Gent

tel : +32 9 264 59 87
Joris.Meys@Ugent.be
-------------------------------
Disclaimer : http://helpdesk.ugent.be/e-maildisclaimer.php

	[[alternative HTML version deleted]]

