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st: Issue with multiple imputation -ICE-

From   René Wevers <>
Subject   st: Issue with multiple imputation -ICE-
Date   Wed, 13 Feb 2008 13:57:06 +0100 (CET)

Dear Statalisters,

I am working with an extensive dataset (10.000+ observations) and
logically some values are missing. I decided to use the -ice- package to
impute certain missing values, but the result simply makes no sense to me.

For instance I am estimating missing variables for the full time
equivalent (FTE) of employees of a company mainly based on the absolute
number of employees. (Logically) the absolute number of employees is never
below zero. Also when I run a regression between the FTE number and
absolute number I get a highly significant relation with positive
coefficient and a positive constant estimates. Nevertheless when I run
-ice-, the imputed values are extremely often (far) below zero (!!!). Also
worrying is that the imputed values are practically all completely
different (over factor 100) from the absolute number of employees, where a
closer relation is (logically) expected.

Is there some explanation for this or are we making any mistakes.

The most basic sytax we would use would look something like this:

ice emptot_fte emptot_abs using "[filename]", boot

(Was also run without bootstrapping and with multiple variables.
Furthermore emptot_abs has no missings)

Many thanks and greetings,


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