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Re: st: mi impute chained


From   ymarchenko@stata.com (Yulia Marchenko, StataCorp)
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: mi impute chained
Date   Thu, 25 Oct 2012 07:21:35 -0500

Chong Shiauyun <shiauyun416@hotmail.com> receives a "no observation" error
when he runs the following imputation model using -mi impute chained-:

> . mi impute chained (reg) birthweight (ologit, augment) ednmatpat 
>    (logit, augment)sex (truncreg, ll(lVIQ) ul(uVIQ))verbiq,
>    add(20) rseed(11349730) burnin(50) chainonly dryrun report

Shiau probably meant to omit the -dryrun- option in the above since 
-mi impute chained- does not perform any estimation when the -dryrun- option
is specified.

The -mi impute chained- command starts off by fitting univariate models on the
observed data to obtain initial imputed values for each imputed variable.  The
"no observation" error typically occurs when one of such models contains no
observations and is often caused by the existence of missing values in
variables other than the imputed variables.  In Shiau's case, the offending
variables may be -lVIQ- and -uVIQ-.

Shiau can use the -noisily- option of -mi impute chained- to identify the
particular conditional model for which there are no observations and run this
model manually on the observed data to determine the problem.

Shiau can also send his data and do file to our technical support group at
tech-support@stata.com to help him identify the problem.


-- Yulia
ymarchenko@stata.com
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