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Re: st: Trying to do some multiple imputation


From   Rose Medeiros <rosem@cisunix.unh.edu>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Trying to do some multiple imputation
Date   Tue, 24 Jan 2006 09:33:26 -0500

Mosi,
If your goal is just to impute values of your income variable, you might use -uvis- which will impute values of the yvar and leave them in your initial dataset. If this is problematic because of a large number of missing values in the variables you are attempting to impute income from, you could use -mvis- and generate only one imputation by specifying m(1) and run your analyses on this dataset (which would also have imputed values for the other variables). Note that both of these procedures are single imputation, rather than multiple imputation. If you actually want to do multiple imputation, you would want to use -micombine- to specify the actual models you want to test, not the variables you are trying to impute.
Best,
Rose

Mosi A. Ifatunji wrote:


Good people,

Here is my quandary. I am having a heck of a time trying to complete
procedures for multiple imputation using Stata 8.2.

My goal is to impute missing values for my income variable (v1019). I would
like to generate 5 new and complete datasets from which to derive my new
values (to be placed back into the old dataset). Here is the syntax I have
been using to no avail:

First, I use the MVIS command to generate five new datasets with values for
any missing values in the key variables:

mvis v1019 black male age2 educate using imp, m(5) genmiss(m_) cmd(regress)
cy(20) se(101) replace

And I get...

imputing 1..2..3..4..5..file imp.dta saved

Then, I open the new dataset (with all missing values imputed):

use imp, clear

Then I generate a model (from the 5 new datasets in imp.dta) that predicts
my income variable (v1019):

micombine regress v1019 black male age2 educate

Multiple imputation parameter estimates (5 imputations)
----------------------------------------------------------------------------
v1019 | Coef. Std. Err. t P>|t| [95% Conf. Interval]
-------------+-------------------------------------------------------------
black | -16060.96 2412.319 -6.66 0.000 -20794.22 -11327.7
male | 10331.52 2487.338 4.15 0.000 5451.057 15211.97
age2 | -114.4879 90.15501 -1.27 0.204 -291.3829 62.40716
educate | 4532.232 722.751 6.27 0.000 3114.107 5950.357
_cons | -8530.671 12416.8 -0.69 0.492 -32893.94 15832.6
----------------------------------------------------------------------------
1106 observations.

Now what do I do? I have been roaming through manuals and copies of the
Stata Journal (4-3 and 5-4) but every time to get near, the author(s) leave
out something important, like how exactly do I use MISET, MI SPLIT AND
MIJOIN to get my imputed values back to my original dataset....

Any help would be greatly appreciated...

M.


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--
Rose Anne Medeiros
Department of Sociology / Family Research Laboratory
University of New Hampshire
126 Horton Social Science Center
20 College Road
Durham, NH 03824
U.S.A.

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