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Re: st: emptycells(reweight)
From
Steve Samuels <[email protected]>
To
[email protected]
Subject
Re: st: emptycells(reweight)
Date
Mon, 20 Jan 2014 11:53:44 -0600
Giuseppina
The output is correct. You are apparently under the impression that the
-emptycells(reweight)- option will modify cell means. It doesn't; it
only changes the weight given to the existing (non-missing) means.
According to the manual:
"emptycells(reweight) specifies that the effects of the observed cells
be increased to accommodate any missing cells. This makes the margin
estimable but changes its interpretation."
Nothing is said about changing anything in the missing cells.
The purpose of -emptycells(reweight)- is to make it possible to estimate
lower-order margins in the presence of missing cells.
To see what is going on, try the following with and without the
-asbalanced- and -emptycells(reweight)- options.
margins timing
margins sexpart
Steve
[email protected]
On Jan 16, 2014, at 11:48 AM, Valle, Giuseppina wrote:
Hello,
I am trying to estimate margins for an interaction term (3 x 5), but I have an empty cell. In order to reconcile this, have tried to use the emptycells(reweight) option. However, I am still getting the following:
This is from the regression:
timing#sexpart |
1 1 | 0 (empty)
1 3 | -.8425747 1.120406 -0.75 0.453 -3.059825 1.374676
1 4 | -.3740791 1.035008 -0.36 0.718 -2.42233 1.674172
1 5 | -1.175772 .8898283 -1.32 0.189 -2.936716 .5851718
3 1 | -.6043734 .5221451 -1.16 0.249 -1.637683 .4289364
3 3 | -.203632 .3666424 -0.56 0.580 -.9292065 .5219424
3 4 | 1.250838 .5659914 2.21 0.029 .130758 2.370919
3 5 | -.6449708 .4828192 -1.34 0.184 -1.600456 .3105142
This is from the margins using the following syntax:
margins timing#sexpart, subpop(if gender==1) asbalanced emptycells(reweight)
Predictive margins Number of obs = 4886
Subpop. no. obs = 2082
Model VCE : Linearized
Expression : Pr(drinkw4), predict()
Empty cells : reweight
at : timing (asbalanced)
race (asbalanced)
famstw1 (asbalanced)
respeduc (asbalanced)
respinc (asbalanced)
sexpart (asbalanced)
--------------------------------------------------------------------------------
| Delta-method
| Margin Std. Err. z P>|z| [95% Conf. Interval]
---------------+----------------------------------------------------------------
timing#sexpart |
1 1 | . (not estimable)
1 2 | .2007178 .1292118 1.55 0.120 -.0525326 .4539682
1 3 | .1723023 .0888076 1.94 0.052 -.0017573 .3463619
1 4 | .2542255 .1413226 1.80 0.072 -.0227617 .5312126
1 5 | .2081755 .0813572 2.56 0.011 .0487182 .3676327
2 1 | .0763753 .0326297 2.34 0.019 .0124223 .1403284
2 2 | .1468328 .0297079 4.94 0.000 .0886064 .2050593
2 3 | .2425471 .0450327 5.39 0.000 .1542846 .3308096
2 4 | .2508539 .0537633 4.67 0.000 .1454798 .356228
2 5 | .3561694 .0553567 6.43 0.000 .2476723 .4646665
3 1 | .0494258 .0169824 2.91 0.004 .0161408 .0827107
3 2 | .1634568 .0325718 5.02 0.000 .0996172 .2272964
3 3 | .2301516 .0512481 4.49 0.000 .1297071 .3305962
3 4 | .552356 .1150508 4.80 0.000 .3268606 .7778514
3 5 | .2537699 .0858682 2.96 0.003 .0854713 .4220684
--------------------------------------------------------------------------------
Is there something I am doing incorrectly? I have read much of what is the stata manual regarding this command, but it seems to still not be working. Any advice would be greatly appreciated!
Thanks,
Pina
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