Re: st: mfx failing with tobit?

[Roger Cremades Rodeja <ecosafor@gmail.com>]

Dear Maarten and colleagues,

using stata 12, and trying to obtain the marginal estimates after a
Tobit regression, I write:

tobit indepvar depvar1 depvar2 .. depvar9, ll
margins, dydx (*)

the second command is supposed to provide the "estimate marginal
effect of variables in varlist", after checking the help of margins,
but I only get again the same coefficients as in the Tobit
regressions, but labelled as dy/dx

I do not know what should I do to obtain the marginal estimates of a
Tobit, I understood that was the right way,

any suggestion would be more than welcome,

Best wishes,
Roger



2014-03-17 17:30 GMT+01:00 Roger Cremades Rodeja <ecosafor@gmail.com>:
> Dear Marteen,
> it was extremely helpful, I will see what can I do with stata 10, or
> use the 12th of a colleague,
> always grateful for your comments
> Best wishes,
> Roger
>
> 2014-03-17 14:26 GMT+01:00 Maarten Buis <maartenlbuis@gmail.com>:
>> -mfx- is a general purpose program, so it needs to choose a default
>> outcome for which to compute the derivative. It chooses that default
>> to be the default chosen for the predict option of the command, which
>> in the case of -tobit- happens to be the linear predictor. So the
>> default marginal effect computed for -tobit- is just the coefficients.
>> If you want to change that, you need to specify the -predict()- option
>> to whatever outcome you are interested in.
>>
>> Notice however, that since you did not specify the version of Stata
>> you are using we must, per the Statalist FAQ, assume you use the
>> latest version of Stata (13). In that case the -mfx- command is
>> hopelessly outdated, and you should use the -margins- command instead.
>>
>> Hope this helps,
>> Maarten
>>
>>
>> On Mon, Mar 17, 2014 at 11:13 AM, Roger Cremades Rodeja
>> <ecosafor@gmail.com> wrote:
>>> Dear colleagues,
>>>
>>> after running a Tobit regression, I introduce the mfx command and
>>> surprisingly I get exactly the same coefficient estimates I had from the
>>> regression, although labelled as dy/dx. Does anybody had a similar problem?
>>>
>>> Please any suggestions to solve it? They would be more than welcome.
>>>
>>> Best wishes,
>>> Roger
>>> *
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>>
>>
>>
>> --
>> ---------------------------------
>> Maarten L. Buis
>> WZB
>> Reichpietschufer 50
>> 10785 Berlin
>> Germany
>>
>> http://www.maartenbuis.nl
>> ---------------------------------
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