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From |
"Joao Ricardo F. Lima" <jricardofl@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: mfx |

Date |
Sat, 19 Jul 2008 14:01:26 -0300 |

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/

**Follow-Ups**:**Re: st: mfx***From:*"Chiara Mussida" <cmussida@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>

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