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st: Logistic Regression Coefficients Using MIM and SVY

From   Steven Frenk <>
Subject   st: Logistic Regression Coefficients Using MIM and SVY
Date   Wed, 31 Mar 2010 11:25:00 -0400

  I am estimating logistic regression models using STATA/SE 10.1 (Windows) and
the MIM and SVY commands.  The models include my dependent variable and one of
my independent variables [mim: svy: logit DV IV, or].

  In four of my models, I get weird parameter estimates?the odds ratio and
CI?s are whole numbers and the standard error is zero. For example:

. mim: svy: logit z_tot_alldisorders z_totprogs06, or

Multiple-imputation estimates (svy: logit)               Imputations =       5
Survey: Logistic regression                              Minimum obs =    1499
                                                         Minimum dof =  1000.0

z_tot_alld~s | Odds Rat.  Std. Err.     t    P>|t|    [95% Conf. Int.]     FMI
z_totprogs06 |         1         0    7.53   0.000          1        2       .

The problem does not exist when I just use the SVY command:

. svy: logit z_tot_alldisorders z_totprogs06, or
(running logit on estimation sample)

Survey: Logistic regression

Number of strata   =         1                  Number of obs      =      7495
Number of PSUs     =      7495                  Population size    = 7485.1806
                                                Design df          =      7494
                                                F(   1,   7494)    =    283.75
                                                Prob > F           =    0.0000

             |             Linearized
z_tot_alld~s | Odds Ratio   Std. Err.      t    P>|t|     [95% Conf. Interval]
z_totprogs06 |   1.469695   .0335955    16.84   0.000     1.405292     1.53705

 This is only occurring with four of my thirteen independent variables. 
Here?s some information about the four variables with the strange estimates:
--Two of them are continuous variables and two are dummy variables.
--Three had missing values (imputed with ice), and one did not have any missing
--When I run logistic models with each imputed data set and use the svy: logit
command, the parameter estimates produced are logical and valid (so I don't
think it is an imputation problem).

  I've tried looking on google and statalist for information regarding this
problem, but I have not found any answers.  Does anyone know why this is
occurring and how to fix it?

Thank you for your time.

Steven M. Frenk
PhD Candidate
Department of Sociology
Duke University
(919) 672-7495

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