[R] NLME Covariates

[Andrew Perrin]

I am foggy on this myself, but I *think* it is inferred from the grouping
structure in the call to (n)lme or in the groupedData data structure. Have
a look at ?groupedData in R for more details.

ap

----------------------------------------------------------------------
Andrew J Perrin - http://www.unc.edu/~aperrin
Assistant Professor of Sociology, U of North Carolina, Chapel Hill
clists at perrin.socsci.unc.edu * andrew_perrin (at) unc.edu


On Wed, 25 Jun 2003, Harold Doran wrote:

> Dear list
>
> In HLM, one can specify a covariate at one of the "levels". For example, if the data structure are repeated observations nested within students nested within schools, school size might be a covariate that is used at level 3, but not at the other levels. In HLM this is rather easy to do.
>
> However, how can one specify a covariate in R for only one of the levels? I have a sample data set with the structure as described above. I fit the unconditional model in R as
>
> model1<-lme(math~year, random=~year|schoolid/childid, data=datafile)
>
> Now, if I want to enter "female" as a covariate at level 2 only, how might I modify the code to accomplish this?
>
> ------
> Harold C. Doran
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> New American Schools
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