--- Ren� Wevers <[email protected]> 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
emptot_fte.
I would definately not use -impute-. The logic against -impute-
explained here:
http://www.stata.com/statalist/archive/2007-12/msg00507.html
IMHO -impute- is one of the few offical Stata commands that StataCorp
should consider withdrawing.
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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