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From |
Michael Norman Mitchell <Michael.Norman.Mitchell@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: RE: Interpretation of quadratic terms |

Date |
Fri, 12 Mar 2010 10:11:26 -0800 |

Dear Rodolphe

I hope that helps, Michael N. Mitchell See the Stata tidbit of the week at... http://www.MichaelNormanMitchell.com On 2010-03-12 3.55 AM, Rodolphe Desbordes wrote:

Dear Michael, In that case, -margins- behaviour is slightly puzzling. Could the absence of output be explained by the fact that the year 1970 did not exist in your sample? . sysuse nlsw88, clear (NLSW, 1988 extract) . . generate year = age + 1968 . end of do-file . tab year year | Freq. Percent Cum. ------------+----------------------------------- 2002 | 53 2.36 2.36 2003 | 260 11.58 13.94 2004 | 257 11.44 25.38 2005 | 225 10.02 35.40 2006 | 219 9.75 45.15 2007 | 234 10.42 55.57 2008 | 208 9.26 64.83 2009 | 222 9.88 74.71 2010 | 160 7.12 81.83 2011 | 165 7.35 89.18 2012 | 163 7.26 96.44 2013 | 78 3.47 99.91 2014 | 2 0.09 100.00 ------------+----------------------------------- Total | 2,246 100.00 Best regards, Rodolphe ________________________________________ From: owner-statalist@hsphsun2.harvard.edu [owner-statalist@hsphsun2.harvard.edu] On Behalf Of Michael Norman Mitchell [Michael.Norman.Mitchell@gmail.com] Sent: 12 March 2010 07:33 To: statalist@hsphsun2.harvard.edu Subject: Re: st: RE: Interpretation of quadratic terms 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. * * 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/ * * 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/* * 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/ * * 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/

* * 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/

**Follow-Ups**:**RE: st: RE: Interpretation of quadratic terms***From:*Rodolphe Desbordes <rodolphe.desbordes@strath.ac.uk>

**References**:**Re: st: RE: Interpretation of quadratic terms***From:*Rosie Chen <jiarongchen2002@yahoo.com>

**RE: st: RE: Interpretation of quadratic terms***From:*Rodolphe Desbordes <rodolphe.desbordes@strath.ac.uk>

**RE: st: RE: Interpretation of quadratic terms***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

**Re: st: RE: Interpretation of quadratic terms***From:*Michael Mitchell <Michael.Norman.Mitchell@gmail.com>

**RE: st: RE: Interpretation of quadratic terms***From:*Rodolphe Desbordes <rodolphe.desbordes@strath.ac.uk>

**RE: st: RE: Interpretation of quadratic terms***From:*DE SOUZA Eric <eric.de_souza@coleurope.eu>

**RE: st: RE: Interpretation of quadratic terms***From:*Rodolphe Desbordes <rodolphe.desbordes@strath.ac.uk>

**Re: st: RE: Interpretation of quadratic terms***From:*Michael Norman Mitchell <Michael.Norman.Mitchell@gmail.com>

**RE: st: RE: Interpretation of quadratic terms***From:*Rodolphe Desbordes <rodolphe.desbordes@strath.ac.uk>

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