p.dalgaard@biostat.ku.dk writes:
Try this
data(Assay)
as1 <- lme(logDens~sample*dilut, data=Assay,
random=pdBlocked(list(
pdIdent(~1),
pdIdent(~sample-1),
pdIdent(~dilut-1))))
update(as1,random=pdCompSymm(~sample-1))
update(as1,random=pdCompSymm(~sample-1))
update(as1,random=pdCompSymm(~sample-1))
update(as1,random=pdCompSymm(~sample-1))
I'm getting different results on different invocations!
I'm not sure exactly what the problem was but it could be triggered by
calling lme directly rather than through update. That is, successive
calls to
lme(logDens~sample*dilut, data=Assay, random=pdCompSymm(~sample-1))
would alternate between a successful fit and an error.
The problem does *not* occur with the current r-patched, which will be
released as R-1.7.1 in early June.