[R-sig-ME] Sample size and mixed models

[Andrew Robinson]

Hi Rob,

On Fri, Dec 12, 2008 at 09:21:15AM -0500, Robert Kushler wrote:
> 
> I would argue that the larger value (individuals) is always more appropriate
> than the smaller value (clusters).  

That's interesting - I have the opposite response, or at least that
the truth lies somewhere in the middle.  Can you expand on why you
would argue that the larger value is always more appropriate than the
smaller value?

> However, the more important issue is that the "ungrouped" version of
> the likelihood should be used for these calculations.  Using the
> "grouped data" likelihood omits the within cluster variation and
> inflates the estimate of predictive power.

I don't follow what you mean by "grouped" and "ungrouped" versions of
the likelihood.  Can you clarify?

Cheers,

Andrew

-- 
Andrew Robinson  
Department of Mathematics and Statistics            Tel: +61-3-8344-6410
University of Melbourne, VIC 3010 Australia         Fax: +61-3-8344-4599
http://www.ms.unimelb.edu.au/~andrewpr
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