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RE: st: Issue with multiple imputation -ICE-

From   Maarten buis <>
Subject   RE: st: Issue with multiple imputation -ICE-
Date   Wed, 13 Feb 2008 17:02:53 +0000 (GMT)

--- René Wevers <> wrote:
> The absolute number of employees does not have any zero values, as
> would be expected. Thus it is still a complete mystery to me why
> negative values appear after imputation.
> I am now applying the -impute- command from Stata, which seems to
> perform better. However, there are also dummy variables which need to
> be imputed. This becomes a bit messy when applying the -impute-
>  command since no estimation technique can be selected (-logit- 
> instead of -regress-).
> I am now thinking of applying -impute- and then rounding the results
> for  the dummies, since these dummy variables are not very important
> for my analysis (only for control). I know it isn't very pretty, but
> I don't see any other (simple) solutions.

I sympathise with your despair: Multiple Imputation sounds easy but
when you try to apply it to real data it pretty soon gets very messy.
My guess is still that there is a problem with your data which you need
to solve first. One thing you might want to look at is this:

gen mis = missing(emptot_fte)
twoway kdensity emptot_abs if mis == 1 ||   ///
       kdensity emptot_abs if mis == 0 ,    ///
       xtitle("number of employees")        ///
       legend(order( 1 "missing fte"        ///
                     2 "not missing fte"))

This way you can see if there is anything "weird" going on with the
distribution of emptot_abs for the companies with missing values on

I would definately not use -impute-. The logic against -impute-
explained here:

IMHO -impute- is one of the few offical Stata commands that StataCorp
should consider withdrawing. 

Hope this helps,

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

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