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st: Imputation of missing values/dealing with multiple imputations in Stata


From   "Andrea Baccarelli" <andreastata5@hotmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   st: Imputation of missing values/dealing with multiple imputations in Stata
Date   Thu, 21 Aug 2003 16:38:59 +0000

I am working on a dataset where the exposure of interest was measured in the plasma of the study subjects. The detection limit is variable (it depends on the amount of plasma available for the assay)

Two points:
1. I was suggested to use an imputation method, which assigns a value for each missing measurement by selecting a value from the assumed distribution using maximum likelihood parameter estimates, related to the approach described by Helsel [Helsel DR. Less than obvious - statistical treatment of data below the detection limit. Environ Sci Technol 1990; 24(12):1766-1774.].
I have seen that Stata has different commands to deal with missing values. Does anybody know whether there is any command available to perform this kind of imputation?

2. I need to impute missing values not only one time, but to use multiple imputation to reflect the uncertainty of the estimates (kind of a "bootstrap" procedure).
How to perform the analysis (linear regression, or any other kind of analysis) on the multiple imputations? SAS 8.0 has a new procedure (PROC MIANALYZE, SAS 8.0) that does exactly this.
Does anybody know whether it is possible to do it also in Stata?

Thanks,
Andrea


Andrea Baccarelli, MD, MPH
Genetic Epidemiology Branch
National Cancer Institute / NIH
6120 Executive Blvd. - EPS 7110
Bethesda, MD 20892-7236
Tel. (301)-496-5786
Fax (301)-402-4489
baccarea@mail.nih.gov

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