Hello,
I am running an svy logistic regression model and noticed a sudden
decrease in the number of cases in my sub-population, from a subpop
size of 3130 observed during the bivariate analysis, to a subpop size
of 1968 produced by the multivariate logistic model. I am wondering
what could be causing the issue. Here are twoo fragments: the first
from the bivariate and the second, the multivariate.
Beyond missing values on some variables in the multivariate model,
what could account for this disparity in cases? thanks in advance for
your help in resolving this.
I have applied all the latest updates.
rgds, CY
*** Bivariate Results ***
. svy, subpop(SexActiveHIVNegMale): logit V781_R Year2534
(running logit on estimation sample)
Survey: Logistic regression
Number of strata = 200 Number of obs = 10687
Number of PSUs = 357 Population size = 11252.784
Subpop. no. of obs = 3130
Subpop. size = 3276.3349
Design df = 157
F( 1, 157) = 4.19
Prob > F = 0.0424
------------------------------------------------------------------------------
| Linearized
V781_R | Coef. Std. Err. t P>|t| [95% Conf. Interval]
-------------+----------------------------------------------------------------
Year2534 | 1.060853 .5184369 2.05 0.042 .0368424 2.084864
_cons | -2.539335 .1933592 -13.13 0.000 -2.921256 -2.157414
*** Multivariate ***
. svy, subpop(SexActiveHIVNegMale): logit V781_R Year2534 Year35
NonChristians Primary SecondaryHigherEduc wealth1 wealth2 wealth4
wealth5 ///
> TwoRiskyBehav WantMoreKids
(running logit on estimation sample)
Survey: Logistic regression
Number of strata = 200 Number of obs = 9525
Number of PSUs = 357 Population size = 9969.9646
Subpop. no. of obs = 1968
Subpop. size = 1993.5153
Design df = 157
F( 11, 147) = 3.93
Prob > F = 0.0001
------------------------------------------------------------------------------
| Linearized
V781_R | Coef. Std. Err. t P>|t| [95% Conf. Interval]
-------------+----------------------------------------------------------------
Year2534 | 1.291047 .6174052 2.09 0.038 .0715545 2.510539
Year35 | .6223602 .4980958 1.25 0.213 -.3614732 1.606194
NonChristi~s | -.2284399 .2398172 -0.95 0.342 -.7021241 .2452443
PrimaryEduc | .5837684 .329269 1.77 0.078 -.0666002 1.234137
SecondaryH~c | .354775 .2689387 1.32 0.189 -.1764297 .8859798
wealth1 | -.4953019 .3694412 -1.34 0.182 -1.225018 .2344144
wealth2 | -.5417754 .2990481 -1.81 0.072 -1.132452 .0489011
wealth4 | .8858961 .3466728 2.56 0.012 .2011517 1.57064
wealth5 | .9065355 .2816133 3.22 0.002 .3502959 1.462775
TwoRiskyBe~v | .4633936 .3322442 1.39 0.165 -.1928516 1.119639
WantMoreKids | .4557333 .3714754 1.23 0.222 -.2780009 1.189468
_cons | -3.720843 .7599802 -4.90 0.000 -5.221947 -2.219738
------------------------------------------------------------------------------
Note: strata with single sampling unit centered at overall mean.
.
end of do-file
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