Re: st: RE: Interpretation of quadratic terms

[Michael Norman Mitchell <Michael.Norman.Mitchell@gmail.com>]

Dear Rodolphe

  Thanks for your message. I think it is possible that you read a 
little bit more into my message than I intended... I was not purporting 
to compute marginal effects, and hence did not use the "dydx()" option. 
I was just showing how to compute the predicted value of "y" for a given 
value of "x". That is another way that the margins command can be used.
Best regards,

Michael N. Mitchell
See the Stata tidbit of the week at...
http://www.MichaelNormanMitchell.com

On 2010-03-11 8.32 AM, Rodolphe Desbordes wrote:
> Dear Eric,
>
> I apologise for my lack of clarity regarding the -margins- command. Even though I have hardly used it, exchanges on the Statalist have made it clear that -margins- can do many things, including the calculation of marginal effects. However Michael did not seem to have used the correct syntax; I believe that the option "dydx" must be used to obtain marginal effects.
>
>   Rodolphe
>
> ________________________________________
> From: owner-statalist@hsphsun2.harvard.edu [owner-statalist@hsphsun2.harvard.edu] On Behalf Of DE SOUZA Eric [eric.de_souza@coleurope.eu]
> Sent: 11 March 2010 15:01
> To: 'statalist@hsphsun2.harvard.edu'
> Subject: RE: st: RE: Interpretation of quadratic terms
>
> Dear Rodolphe,
>
> I don't have Stata 11 either. But according to the preface to the new edition of Cameron and Trivedi, Microeconometrics using Stata:
> "Second, we describe the new margins command for prediction and for computation of
> marginal effects in regression models. The margins command with options including the
> dydx() option replaces the Stata mfx command and the user-written margeff command.
> Additionally, the margins command when used in conjunction with factor variables can
> simplify computation of marginal effects in models with interactions. "
>
> So the margins command is Stata 11 does allow one to calculate marginal effects
>
> Eric de Souza
> College of Europe
> BE-8000 Brugge (Bruges)
> Belgium
>
> -----Original Message-----
> From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Rodolphe Desbordes
> Sent: 11 March 2010 14:59
> To: statalist@hsphsun2.harvard.edu
> Subject: RE: st: RE: Interpretation of quadratic terms
>
> I do not have Stata 11 installed on this computer and I am not vary familiar with the -margins- command. However, using -margins-, you did not calculate the marginal effect but the predicted value of wage, at a given value of age.
>
>
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