# Re: st: Re: Stata 11 imputation

 From Fred Wolfe To statalist@hsphsun2.harvard.edu Subject Re: st: Re: Stata 11 imputation Date Mon, 27 Jul 2009 14:38:58 -0500

```I found the following slightly more recent papers:

Using Calibration to Improve Rounding in Imputation
Recai M Yucel, Yulei He, Alan M Zaslavsky. The American Statistician.
May 1, 2008, 62(2): 125-129. doi:10.1198/000313008X300912.

Robustness of a multivariate normal approximation for imputation of
incomplete binary data
Coen A. Bernaards, Thomas R. Belin, Joseph L. Schafer
Statistics in Medicine Volume 26 Issue 6, Pages 1368 - 1382 (2006)

which seem to say its OK to round binary data if you do it correctly,
though I have only seen the abstracts (don't have access to the paper
from where I am).

Fred Wolfe

On Mon, Jul 27, 2009 at 11:31 AM, Joseph Coveney<jcoveney@bigplanet.com> wrote:
> Fred Wolfe wrote:
>
> I have been reading the Stata 11 imputation manual. .
>
> The manual states (page 107), "In practice, multiple variables usually
> must be imputed simultaneously, and that requires using a multivariate
> imputation method. The choice of an imputation method in this case
> depends on the pattern of missing values." In my instance this means
> using -mi impute mvn-
>
> Using Royston's multivariate -ice-, it was possible to specify
> mulivariate  matching, oligit, mlogit, and logit. This is not possible
> with -mi impute mvn -. From a users point of this means out of usual
> (expected) range values (e.g., ages <0, non-integer categorical
> values). The manual suggests (page 109), "For multiple categorical
> variables with only two categories (binary or dummy variables), a
> multivariate normal approach ([MI] mi impute mvn) can be used to
> impute missing values and then round the imputed values to 0 if the
> value is smaller than 0.5, or 1 otherwise. For categorical variables
> with more than two categories, Allison (2001) describes how to use the
> normal model to impute missing values."
>
>
> I wonder if it might be possible in a revision of the manual to
> actually describe how to impute categorical values without having to
> purchase Allison's book (available on Amazon.com at a reasonable
> cost). [remainder omitted]
>
> --------------------------------------------------------------------------------
>
> These appear to give some insight as to what Paul Allison's book might be
> saying.
>
> www2.sas.com/proceedings/sugi30/112-30.pdf
>
> www2.sas.com/proceedings/sugi30/113-30.pdf
>
> Their message now seems to be not to round at all.
>
> Joseph Coveney
>
>
>
> *
> *   For searches and help try:
> *   http://www.stata.com/help.cgi?search
> *   http://www.stata.com/support/statalist/faq
> *   http://www.ats.ucla.edu/stat/stata/
>

--
Fred Wolfe
National Data Bank for Rheumatic Diseases
Wichita, Kansas
NDB Office  +1 316 263 2125 Ext 0
Research Office +1 316 686 9195
fwolfe@arthritis-research.org

*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/
```