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# Re: st: Obtaining rrr's of margins after mlogit

 From John Francis To statalist@hsphsun2.harvard.edu Subject Re: st: Obtaining rrr's of margins after mlogit Date Thu, 22 Mar 2012 11:31:02 +0100

```Thank you Maarten,

That part I had figured out already. Please let me respecify: what I
want is to first run
-mlogit-, say

.mlogit depvar i.edu##i.coh i.sex##i.coh, b(2) nolog

Then, I would first like to get the marginal effects for each outcome
in order to get RRRs of the interaction terms, with each of the four
categories in relation to category 2. The reason I want to do this is
so that I can use the method described in your Stata-Tip regarding the
interpretation of interaction effects in nonlinear models. This means
that I
would run

.forval i = 1/4 {
.margins, over(i.edu i.coh) expr(exp(xb(#`i'))) post
.est sto m`i'
.}

so that afterwards, I could use -lincom- in order to interpret the
interaction effects as RRRs. Same goes for the interaction of sex and
coh. This is how far I got so far. Now of course, Stata tells me
"Warning: prediction constant over observations." I take that to mean
that the specification of xb() is wrong, yet I don't know how I should
change it.

Besides, is this the correct way to apply the procedure described by
you to a multinomial logit model?

Regards,
John

On Thu, Mar 22, 2012 at 9:14 AM, Maarten Buis <maartenlbuis@gmail.com> wrote:
> On Wed, Mar 21, 2012 at 5:37 PM, John Francis wrote:
>> I have a question on obtaining margins as relative risk ratios instead
>> of probabilities after I run the mlogit command.
>
> You can specify the -rrr- option in -mlogit-.
>
> Hope this helps,
> Maarten
>
> --------------------------
> Maarten L. Buis
> Institut fuer Soziologie
> Universitaet Tuebingen
> Wilhelmstrasse 36
> 72074 Tuebingen
> Germany
>
>
> http://www.maartenbuis.nl
> --------------------------
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```