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Re: st: multi-level modeling with multiple imputed data in STATA


From   Maarten buis <maartenbuis@yahoo.co.uk>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: multi-level modeling with multiple imputed data in STATA
Date   Thu, 15 Mar 2007 21:16:33 +0000 (GMT)

-- tdavis7@emory.edu wrote:
> However, it doesn't appear that Stata supports multi-level modeling
> with any of the imputed data commands (mifit for example).  It also
> does not appear that gllamm or xtmixed support multiple imputed data.
> Am I correct?

Yes, but this is not a big problem, since you can do it by hand. You
can find the necessary formula's at:
http://www.stat.psu.edu/~jls/mifaq.html#howto

Basically the point estimates are the mean estimates over the different
datasets, and the standard errors are the square root of the mean
variances plus a simple to compute correction factor.

> I would think that Stata can combine the variables from the imputed
> data sets into an average data set?  Is this correct?  If so, is this
> even prudent?

This would be a bad idea. The whole point of multiple imputation is
that
you get multiple datasets, and multiple estimates. It is the
differences
between the estimates that tells us about the uncertainty due to
imputation and go into the correction factor for the computation of the
standard error.

Hope this helps,
Maarten


-----------------------------------------
Maarten L. Buis
Department of Social Research Methodology
Vrije Universiteit Amsterdam
Boelelaan 1081
1081 HV Amsterdam
The Netherlands

visiting address:
Buitenveldertselaan 3 (Metropolitan), room Z434

+31 20 5986715

http://home.fsw.vu.nl/m.buis/
-----------------------------------------


	
	
		
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