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

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: mfx |

Date |
Mon, 21 Jul 2008 15:07:44 +0200 |

At this stage it is better to ask: the command below only allow to get the mfx for continuous variables? this is also because, by trying with a discrete, you get the error message below. Again: is there a way to obtain a range for y? it would be nice, since the dep var in my model covers a wide range if values!! Thanks and Sorry for the absence of details below! 2008/7/21 Arne Risa Hole <arnehole@gmail.com>: > 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/ > -- 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>

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

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

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