Re: st: Question about XTMIXED command (fwd)

[Laura Gibbons <gibbonsl@u.washington.edu>]

I would create a new variable that is baseline BMI.

bys unqid (year):gen baselinebmi=bmi[1]

On 3/7/2014 9:22 AM, Christina Wei wrote:
> Hi all,
>
> I am using Stata version 12.  New to data analysis using the long format.
>
> My question is:  I am trying to do a multilevel data analysis involving
> data collected from 100 patients over 3 visits.  I would like to adjust for
> baseline BMI, but in the long format BMI is collected over 3 visits and BMI
> from all 3 visits look like they will appear in the model if I were to
> insert it into the command as followed:
>
> xtmixed y i.female bmi age  || unqid:year, covariance(unstructured)  ||
> bmi:year,covariance(unstructured)
>
> How can I include baseline BMI (visit 1) as the variable that I would like
> to add to the model?
>
> Thanks for your help,
> Christina
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--
Laura E. Gibbons, PhD
General Internal Medicine, University of Washington
Box 359780, Harborview Medical Center, 325 Ninth Ave, Seattle, WA 98104
phone: 206-744-1842, fax: 206-897-4688,
Office address: 1449 Ninth and Jefferson Building
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*
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*   http://www.ats.ucla.edu/stat/stata/