Hi Everyone,
I'm running a survey-weighted regression model with marginal means estimates. I noticed that over() and at() do not produce equivalent results and I was unsure why. Here's the relevant portion of the regression output. There were no interaction terms and there were a dozen covariates.
When I ran the margins command initially it was:
By happenstance I happened to enter a different margins specification the next time I ran the model, and got different results
I was curious why these did not produce the same estimates. relid was not interacted with anything and both models used the <atmeans> option. Could someone clarify what I am missing here?
Thanks!
David.
I'm running a survey-weighted regression model with marginal means estimates. I noticed that over() and at() do not produce equivalent results and I was unsure why. Here's the relevant portion of the regression output. There were no interaction terms and there were a dozen covariates.
Code:
relid |
------------------------------------------------------------------------------
| Linearized
dv | Coef. Std. Err. t P>|t| [95% Conf. Interval]
-------------+----------------------------------------------------------------
relid |
Agnostics | -.2154432 .0940226 -2.29 0.022 -.3998531 -.0310333
OtherNones | -.244422 .1706986 -1.43 0.152 -.5792192 .0903751
NIPs | -.2634163 .0966674 -2.72 0.006 -.4530134 -.0738191
Protestants | -.5831272 .0987427 -5.91 0.000 -.7767946 -.3894598
Catholics | -.4672434 .0953257 -4.90 0.000 -.6542089 -.2802779
Christians | -.3771565 .182936 -2.06 0.039 -.7359551 -.0183579
Code:
margins, at(relid = (0 1 2 3 4 5 6)) atmeans pwcomp(pv)
-----------------------------------------------------
| Delta-method Unadjusted
| Contrast Std. Err. t P>|t|
-------------+---------------------------------------
_at |
2 vs 1 | -.2154432 .0940226 -2.29 0.022
3 vs 1 | -.244422 .1706986 -1.43 0.152
4 vs 1 | -.2634163 .0966674 -2.72 0.006
5 vs 1 | -.5831272 .0987427 -5.91 0.000
6 vs 1 | -.4672434 .0953257 -4.90 0.000
Code:
margins, over(relid) atmeans pwcomp(pv)
-------------------------------------------------------------------
| Delta-method Unadjusted
| Contrast Std. Err. t P>|t|
---------------------------+---------------------------------------
relid |
Agnostics vs Atheists | -.2330303 .0940864 -2.48 0.013
OtherNones vs Atheists | -.5501877 .1735495 -3.17 0.002
NIPs vs Atheists | -.5491664 .0929277 -5.91 0.000
Protestants vs Atheists | -1.014815 .0815914 -12.44 0.000
Catholics vs Atheists | -.8043829 .0848022 -9.49 0.000
Christians vs Atheists | -.8228742 .1765394 -4.66 0.000
Thanks!
David.
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