Dear Rafel,
Your description of the data and research question are not very clearly
stated. However, the question about extracting random effects and the nature
of conditional modes has been discussed in the past fortnight on this list.
Look for postings by Reinhold Kleigl.

Best wishes, Nick

2009/1/28 Rafael Maia <queirozrafaelmv@yahoo.com.br>

> Dear list members,
>
> I am analyzing a data set comprised of two variables measured over time
> (once a month, over a year, for a total of 12 observations per individual).
> I am interested in modeling the relationships between these two variables,
> but I'd like specifically to compare if individual variation over time is
> associated between them. There is great individual variation in slopes for
> both variables, and I'd like to measure the degree of intra-individual
> association between the slopes for the two.
>
> My first intuition was to conduct random slopes models for the variables
> and compare random effects (conditional modes for the slope?). However, I
> recall reading in some slides from Douglas Bates that these are not actually
> "estimates", actually something more similar to predictors. I also think I
> remember someone mentioning on this list specifically that these values
> should not be extracted and used as parameters for other analyses.
>
> If this was not a mixed-model "situation", I guess it would be reasonable
> to compare regression slopes through an analysis of covariance, for example.
> Anyone has any suggestion as to how to treat this case? Any help would be
> greatly appreciated.
>
> Many thanks in advance!
>
> Abraços,
> Rafael Maia
> ---
> "A little learning is a dangerous thing; drink deep, or taste not the
> Pierian spring." (A. Pope)
> M.Sc., Animal Behavior Lab - Dept. of Zoology
> Universidade de Brasilia, Brazil
> http://www.unb.br/ib/zoo/rhmacedo/
>
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