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Re: st: mi import + xtmixed
From
[email protected] (Wes Eddings, StataCorp)
To
[email protected]
Subject
Re: st: mi import + xtmixed
Date
Wed, 09 May 2012 14:55:54 -0500
Elizabeth Covay ([email protected]) asked about using -mi import- with a
longitudinal dataset, where the dataset had been subdivided, imputed in -ice-,
and then re-combined:
> We used the -ice- command for multiple imputation for a longitudinal data set.
> The data was in three separate files (one for each wave) when we did the
> multiple imputation. We have since combined these three waves into one
> longitudinal data set where each student is in the data set for each wave and
> for each multiply imputed data set (3 waves x 10 multiply imputed data sets).
> We are running into problems using the -mi import- command since the student
> id and imputation number id is not a unique combination.
>
> (snip)
>
> Our current solution is to create a new student id that is a combination of
> the original id and the wave so that there is a unique combination of student
> id and imputation number. Once we have the -mi import- done using our new
> student id we plan to use the proper mi estimate command with the original
> student id. Does anyone see problems with this method?
There isn't a problem with this method, but there is another way, one that does
not require a new ID variable. Elizabeth has three files after using -ice-.
She can run -mi import- separately on each of the three files, and then use
-mi append- to join the three -mi- datasets. The commands might look like this:
. use icedata1
. mi import ice, automatic
. save midata1
* (repeat for icedata2 and icedata3)
. use midata1, clear
. mi append using midata2
. mi append using midata3
The -mi append- command works like -append-, but for -mi- data. -mi append-
must be run one time for each -using- dataset to be appended.
--Wes
[email protected]
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