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From |
"Chiara Mussida" <cmussida@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: mfx |

Date |
Mon, 21 Jul 2008 12:21:23 +0200 |

Thanks for all these suggestions!! the twoway function plot perfectly works with the probit formulation. But when I try with a biprobit it says: ; is not a twoway plot type r(198); without claryfing the reasons! 2008/7/19 Joao Ricardo F. Lima <jricardofl@gmail.com>: > Arne > > thanks for your answer. Now I understand that x represents the mpg > variable. I was curious because I had changed the code to: > > #delimit ; > twoway (function y = _b[mpg]*normden(_b[price]*`mean_price'+ > _b[mpg]*mpg+_b[_cons]), range(mpg)) ; > #delimit cr > > and the graph generated was different. > > Best regards, > > Joao Lima > > 2008/7/19 Arne Risa Hole <arnehole@gmail.com>: >> Joao, >> >> What the code below does is plotting the marginal effect of the mpg >> variable evaluated at different values, holding the price variable >> constant at its mean. The x in the code represents the mpg variable - >> see -help twoway function-. >> >> Perhaps this is clearer: >> >> sysuse auto >> probit foreign price mpg >> mfx >> sum price >> local mean_price = r(mean) >> #delimit ; >> twoway (function y = _b[mpg]*normden(_b[price]*`mean_price'+ >> _b[mpg]*x+_b[_cons]), range(mpg) ytitle(Marginal effect) >> xtitle(Miles per gallon)) ; >> #delimit cr >> >> Arne >> >> 2008/7/19 Joao Ricardo F. Lima <jricardofl@gmail.com>: >>> Dear, >>> >>> sorry the simple question. I am curious why I have to use "x" instead >>> mpg (mean) in the twoway graph (..._b[mpg]*x+_b...)? Or better, what >>> Stata understand when I type x in this command? >>> >>> Thanks a lot, >>> >>> Joao Ricardo >>> >>> 2008/7/18 Arne Risa Hole <arnehole@gmail.com>: >>>> Hi Chiara, >>>> >>>> How about this? >>>> >>>> sysuse auto >>>> probit foreign price mpg >>>> mfx >>>> sum price >>>> local mean_price = r(mean) >>>> #delimit ; >>>> twoway (function y = _b[mpg]*normden(_b[price]*`mean_price'+ >>>> _b[mpg]*x+_b[_cons]), range(mpg)) ; >>>> #delimit cr >>>> >>>> This plots the marginal effect of the mpg variable over its range >>>> following a probit regression. The logic is the same with -biprobit- >>>> but the formula for the marginal effect will of course be a little >>>> more intricate in that case. >>>> >>>> Arne >>>> >>>> 2008/7/18 Chiara Mussida <cmussida@gmail.com>: >>>>> Dear All,nuous variab >>>>> is there a way to "plot" the mfx of a continuous variable (after a >>>>> biprobit) to infer its behaviour over the complete range of values and >>>>> not only for the mean of the independent variables (which is the >>>>> default)? >>>>> >>>>> Thanks >>>>> >>>>> -- >>>>> Chiara Mussida >>>>> PhD candidate >>>>> Doctoral school of Economic Policy >>>>> Catholic University, piacenza (Italy) >>>>> * >>>>> * 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/ >>>> >>> >>> >>> >>> -- >>> ------------------------------- >>> Joao Ricardo Lima >>> Professor >>> UFPB-CCA-DCFS >>> +553138923914 >>> ------------------------------- >>> * >>> * 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/ >> > > > > -- > ------------------------------- > Joao Ricardo Lima > Professor > UFPB-CCA-DCFS > +553138923914 > ------------------------------- > * > * 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/ > -- Chiara Mussida PhD candidate Doctoral school of Economic Policy Catholic University, piacenza (Italy) * * 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: mfx***From:*"Arne Risa Hole" <arnehole@gmail.com>

**References**:**st: mfx***From:*"Chiara Mussida" <cmussida@gmail.com>

**Re: st: mfx***From:*"Arne Risa Hole" <arnehole@gmail.com>

**Re: st: mfx***From:*"Joao Ricardo F. Lima" <jricardofl@gmail.com>

**Re: st: mfx***From:*"Arne Risa Hole" <arnehole@gmail.com>

**Re: st: mfx***From:*"Joao Ricardo F. Lima" <jricardofl@gmail.com>

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