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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 14:34:23 +0100 |

Chiara, Try to be a bit more specific when explaining what you want to do... initially you asked for a plot of the marginal effect of a contionous variable which is what the example I sent earlier does. With a discrete 0-1 dummy there is nothing to plot as there is only one possible change from 0-1. Arne 2008/7/21 Chiara Mussida <cmussida@gmail.com>: > 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/ > * * 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>

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

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

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