Re: st: RE: RE: problem running mfx after glm

[Richard Williams <richardwilliams.ndu@gmail.com>]

At 06:04 PM 8/15/2011, Marlis Gonzalez Fernandez wrote:
> I am trying to analyze a new variable (categorical 5 levels) still 
> accounting for marginal effects since audcompCombdiv100 is a 
> proportion so I wrote:
> glm  audcompCombdiv100 Age Gender0Male1Female DWIVolume 
> i.Discharge_Location, family(binomial) link(logit) robust
> mfx, at(mean)
>
> -default predict() is unsuitable for marginal-effect calculation
> -r(119);
>
> Is the problem the use of -i.var-?
mfx doesn't like the i. notation. You could compute the dummies 
yourself, but mfx would not be smart enough to know that the dummies 
are all inter-related, e.g. if one dummy = 1 the others all have to 
equal 0. Use margins instead:
margins, dydx(*) atmeans

Also, my own bias would be to drop the -atmeans- option and use the 
default -asobserved- instead.

-------------------------------------------
Richard Williams, Notre Dame Dept of Sociology
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EMAIL:  Richard.A.Williams.5@ND.Edu
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