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


From   Maarten Buis <maartenlbuis@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Obtaining rrr's of margins after mlogit
Date   Thu, 22 Mar 2012 11:41:41 +0100

Maybe I am still not understanding your question, as the solution
appears to me to just not to use -margins- or -lincom- but directly
specify the -rrr- option in your -mlogit- command:

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

This will directly give you the ratio or relative risk ratios that you
seem to be looking for.

Hope this helps,
Maarten

On Thu, Mar 22, 2012 at 11:31 AM, John Francis
<francisj71@googlemail.com> wrote:
> 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
>> --------------------------
>> *
>> *   For searches and help try:
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>> *   http://www.stata.com/support/statalist/faq
>> *   http://www.ats.ucla.edu/stat/stata/
>
> *
> *   For searches and help try:
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-- 
--------------------------
Maarten L. Buis
Institut fuer Soziologie
Universitaet Tuebingen
Wilhelmstrasse 36
72074 Tuebingen
Germany


http://www.maartenbuis.nl
--------------------------

*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/


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