[R] crossed random fx nlme lme4

[Emilio A. Laca]

random = pdBlocked( list( pdIdent( ~ y), pdIdent( ~ observer - 1),  
pdIdent( ~ set - 1) )

gave me output only when the data was a groupedData. The results are  
different depending on whether I specify observer or set as grouping  
factor.
I am missing something ...

Simon, Prof Bates, thanks for taking the time to reply.

eal

On Jul 15, 2005, at 6:35 AM, Douglas Bates wrote:

> On 7/13/05, Simon Blomberg <blomsp at ozemail.com.au> wrote:
>
>> At 09:35 AM 14/07/2005, Emilio A. Laca wrote:
>>
>>> I need to specify a model similar to this
>>>
>>> lme.formula(fixed = sqrt(lbPerAc) ~ y + season + y:season, data =  
>>> cy,
>>>      random = ~y | observer/set, correlation = corARMA(q = 6))
>>>
>>> except that observer and set are actually crossed instead of nested.
>>>
>>
>> Does this work for you? (following P&B pp 162-3 and an R-help archive
>> search on "crossed random effects")...
>>
>> fit <- lme(sqrt(lbPerAc) ~ y * season, random=list(pdBlocked 
>> (pdIdent(~y),
>> pdIdent(observer-1), pdIdent(set-1))), correlation=corARMA(q = 6),  
>> data=cy)
>>
>> lme isn't very well set up for crossed random effects. It's easier  
>> in lmer.
>> I don't think lmer can handle alternative correlation structures yet,
>> though. (Prof. Bates?)
>>
>
> Exactly.  Thanks for the summary.
>
>
>>
>> HTH,
>>
>> Simon.
>>
>>
>>
>>> observer and set are factors
>>> y and lbPerAc are numeric
>>>
>>> If you know how to do it or have suggestions for reading I will be
>>> grateful.
>>>
>>>
>>> eal
>>>
>>> ps I have already read Pinheiro & Bates, the jan 05 newsletter, and
>>> several postings.
>>>
>>> ______________________________________________
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>>> PLEASE do read the posting guide! http://www.R-project.org/ 
>>> posting-guide.html
>>>
>>
>> Simon Blomberg, B.Sc.(Hons.), Ph.D, M.App.Stat.
>> Centre for Resource and Environmental Studies
>> The Australian National University
>> Canberra ACT 0200
>> Australia
>> T: +61 2 6125 7800 email: Simon.Blomberg_at_anu.edu.au
>> F: +61 2 6125 0757
>> CRICOS Provider # 00120C
>>
>> ______________________________________________
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>>
>