[R] Using lme() for split plot
Joshua Stults
joshua.stults at gmail.com
Fri May 8 00:06:28 CEST 2009
I should say I'm using Google books to look at 'Mixed effects
models...' so I can't see pp 49 - 50.
On Thu, May 7, 2009 at 6:02 PM, Joshua Stults <joshua.stults at gmail.com> wrote:
> That's a good example with a couple levels of nesting (similar to the
> examples in the other book), but they still only have one factor,
> 'Variety', nested in each block. Am I missing something? Should I
> make up a psuedofactor with four levels to code my two two-level
> factors?
>
>
> On Thu, May 7, 2009 at 5:46 PM, Rubén Roa-Ureta <rroa at udec.cl> wrote:
>> Joshua Stults wrote:
>>>
>>> Hi,
>>>
>>> I'm trying to figure out how to use lme() for analyzing a split-plot
>>> experiment. I've been looking at the examples from the 'R Book',
>>> those are nested but with only one factor at the whole-plot level, my
>>> test is 2^2 at the whole-plot level, with a single many level factor
>>> at the sub-plot level. My question is about properly specifying the
>>> random effects part of the model,
>>>
>>> lme( y ~ block + a*b*poly(c, n), random=~ ? )
>>>
>>> Where 'a' and 'b' are my two level whole-plot factors and 'c' is the
>>> many level sub-plot factor. I'm not sure what to use to get the right
>>> error terms. Do I use two error terms:
>>>
>>> random = ~ 1 | block/a + 1 | block/b
>>>
>>> or one:
>>>
>>> random = ~ 1 | block/a*b
>>>
>>> or something else entirely? I haven't been able to find any relevant
>>> examples on Google. Thanks for any suggestions/pointers.
>>>
>>>
>>
>> Have you checked Pinheiro and Bates 2004 Mixed-effects models in S and
>> S-PLUS? They have a split-plot example starting on p. 45.
>> Rubén
>>
>
>
>
> --
> Joshua Stults
> Website: http://j-stults.blogspot.com
>
--
Joshua Stults
Website: http://j-stults.blogspot.com
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