Sorry for the late reply. As I indicated in another message, I was at useR!2010 then on vacation. On Tue, Jul 27, 2010 at 7:43 PM, Christoph Scherber
<Christoph.Scherber at agr.uni-goettingen.de> wrote:
Dear all, Let?s assume I have an lme model with the following random effects structure: random=~1|block/plot Now, further treatments are applied at the next smallest level, but they are on the same hierarchy. In lmer notation, this could be parameterized as ...+(1|block/plot/treatment.type1)+(1|block/plot/treatment.type2)
I'm not entirely sure that would be successful. The expansion of the / in the grouping factor in lme4 doesn't do a full symbolic analysis of the terms. Instead it is more of a macro expansion. I think that would probably end up with multiple random-effects terms of the form 1|block and 1|block:plot and a model for which unique parameter estimates are not defined.
How could I specify the same structure in lme?
It would not be easy to do that. In fact, I'm not even sure it is possible. I think my advice would be to stay with simpler model specifications. You would need a huge amount of data to be able to estimate parameters in such a model successfully.
I know that I would need to use one of the pdClasses(), but I don?t understand how to set this up correctly. I tried of course the Pinheiro & Bates book, but maybe someone can give me a hint. That would be excellent! All the best and many thanks for any help, Christoph
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