# st: predictive margins not estimable in svy

 From susan@hailpern.com To statalist@hsphsun2.harvard.edu Subject st: predictive margins not estimable in svy Date Fri, 07 Aug 2009 15:52:47 -0700

```Hello,

I am having problems using the Stata 10 "margins" command with survey
data.

I have a created a subpop of ~2500 observations (total 5000+) and would
like to obtain the age- sex- race adjusted prevalence of my dichotomous
outcome by cystatin-c quartile. Data is svyset; svy logistic model
including age, sex and race and cystatin-c was run, followed by the
marginals command.

The output says (not estimable). (below)

Can anyone help?  I do get estimations if I take it out of survey mode,
Thanks,
Sue

. svy, subpop(subpopnodm): logistic pad i.x age56 sex01 race2
(running logistic on estimation sample)

Survey: Logistic regression

Number of strata   =        28                 Number of obs      =
5684
Number of PSUs     =        57                 Population size    =
230532837
Subpop. no. of obs =
2472
Subpop. size       =
90812359.8
Design df          =
29
F(   6,     24)    =
28.73
Prob > F           =
0.0000

------------------------------------------------------------------------------
|             Linearized
pad | Odds Ratio   Std. Err.      t    P>|t|     [95% Conf.
Interval]
-------------+----------------------------------------------------------------
x |
2  |   1.521746   .5364044     1.19   0.243     .7400256
3.12923
3  |   4.057542   2.135947     2.66   0.013     1.382564
11.90805
4  |   9.510348   3.931692     5.45   0.000     4.083106
22.15145
|
age56 |   4.655526   2.164545     3.31   0.003     1.798843
12.04881
sex01 |    1.14324    .236113     0.65   0.522      .749361
1.744149
race2 |   2.314983   .5035135     3.86   0.001     1.483732
3.611936
------------------------------------------------------------------------------

. margins i.x , subpop(if subpopnodm==1)

Predictive margins                                Number of obs   =
3009
Subpop. no. obs =
2472
Model VCE    : Linearized

------------------------------------------------------------------------------
|            Delta-method
|     Margin   Std. Err.      z    P>|z|     [95% Conf.
Interval]
-------------+----------------------------------------------------------------
x |
1  |  (not estimable)
2  |  (not estimable)
3  |  (not estimable)
4  |  (not estimable)
------------------------------------------------------------------------------

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```