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From |
"Arne Risa Hole" <arnehole@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: mfx |

Date |
Mon, 21 Jul 2008 14:00:00 +0100 |

Chiara, As has been pointed out many times before on the list, the Statalist FAQ section 3.3 says: Say exactly what you typed and exactly what Stata typed (or did) in response. N.B. exactly! If you can, reproduce the error with one of Stata's provided datasets or a simple concocted dataset that you include in your posting. If you do that someone might be able to find the error. Arne 2008/7/21 Chiara Mussida <cmussida@gmail.com>: > 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/ > * * 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>

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

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

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