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# st: Obtaining 95%CI for marginal effect

 From Nur Hafidha Hikmayani To statalist@hsphsun2.harvard.edu Subject st: Obtaining 95%CI for marginal effect Date Sun, 6 Feb 2011 19:02:37 +0700

```Dear all,
I've been running some regression models using -svy- and estimating
its marginal effect using -mfx- (I use Stata 10.1).
I wonder how can I get the 95% CI for the marginal effects (y)?

The output for regression and its marginal effect are as follows:

. xi: svy: reg GH i.medgrp exgrp chronic nummed gp
------------------------------------------------------------------------------
|             Linearized
GH |      Coef.   Std. Err.      t    P>|t|     [95% Conf. Interval]
-------------+----------------------------------------------------------------
_Imedgrp_1 |   4.429839    3.56263     1.24   0.214    -2.564628    11.42431
_Imedgrp_2 |   8.333728   3.633545     2.29   0.022     1.200035    15.46742
_Imedgrp_3 |   10.05818   3.773961     2.67   0.008     2.648813    17.46755
exgrp |  -8.916839    1.89046    -4.72   0.000    -12.62835   -5.205324
chronic |  -10.31767   1.936802    -5.33   0.000    -14.12017   -6.515169
nummed |  -1.063043   .3452676    -3.08   0.002    -1.740902   -.3851831
gp |  -4.347845   1.773649    -2.45   0.014    -7.830027    -.865663
_cons |   83.19335   3.520136    23.63   0.000     76.28231    90.10438
------------------------------------------------------------------------------

. mfx, at(mean _Imedgrp_1=0 _Imedgrp_2=0)
Marginal effects after svy:regress
y  = Fitted values (predict)
=  53.085624
------------------------------------------------------------------------------
variable |      dy/dx    Std. Err.     z    P>|z|  [    95% C.I.   ]      X
---------+--------------------------------------------------------------------
_Imedg~1*|   4.429839     3.56263    1.24   0.214  -2.55279  11.4125         0
_Imedg~2*|   8.333728     3.63354    2.29   0.022   1.21211  15.4553   .379185
_Imedg~3*|   10.05818     3.77396    2.67   0.008   2.66136   17.455         0
exgrp*|  -8.916839     1.89046   -4.72   0.000  -12.6221 -5.21161   .762312
chronic*|  -10.31767      1.9368   -5.33   0.000  -14.1137 -6.52161    .83752
nummed |  -1.063043      .34527   -3.08   0.002  -1.73975 -.386331   6.69376
gp*|  -4.347845     1.77365   -2.45   0.014  -7.82413 -.871558   .472814
------------------------------------------------------------------------------
(*) dy/dx is for discrete change of dummy variable from 0 to 1

Any help is much appreciated,
Thanks,
hafida-

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```