Dear all, In the SASmixed package there is an example of an analysis of a split-plot experiment. The model is fm1Semi <- lme( resistance ~ ET * position, data = Semiconductor, random = ~ 1 | Grp) where Grp in the Semiconductor dataset is defined as ET*Wafer. Is it possible to specify the grouping directly some way, e.g. like fm1Semi <- lme( resistance ~ ET * position, data = Semiconductor, random = ~ 1 | ET*Wafer) (this does not work, I know, but somehow I would expect it to be possible to get around having to define a new variable in the dataset)... Thanks in advance Søren Højsgaard [[alternative HTML version deleted]]
S??ren H??jsgaard <sorenh at agrsci.dk> writes:> Dear all, > In the SASmixed package there is an example of an analysis of a split-plot experiment. The model is > > fm1Semi <- lme( resistance ~ ET * position, data = Semiconductor, random = ~ 1 | Grp) > > where Grp in the Semiconductor dataset is defined as ET*Wafer. Is it possible to specify the grouping directly some way, e.g. like > > fm1Semi <- lme( resistance ~ ET * position, data = Semiconductor, random = ~ 1 | ET*Wafer)Actually that does work with lme from the as-yet-unreleased version 0.6-1 of the lme4 package. See the slides from my presentation at useR!2004 http://www.ci.tuwien.ac.at/Conferences/useR-2004/Keynotes/Bates.pdf I'm back at my home now and will endeavor to get lme4_0.6-1 released as soon as possible. -- Douglas Bates bates at stat.wisc.edu Statistics Department 608/262-2598 University of Wisconsin - Madison http://www.stat.wisc.edu/~bates/