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From |
Ekrem Kalkan <kalkan.ekrem@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: -nlcom- question |

Date |
Thu, 17 Dec 2009 21:56:46 +0200 |

Hello, you need to take a particular point of X , for example its mean or minimum or maximum value. You can do this: sum X gen xbar=r(mean) and then insert "xbar" where it is needed in your nlcom formula I hope this is what you asked. Ekrem Kalkan 2009/12/16 Laurent Piet <Laurent.Piet@rennes.inra.fr>: > Dear list, > > I think my problem can be solved with -nlcom- but I have not figured out how > to do yet. > > I use the “function evaluator program” version of the -nl- command to fit a > parametric Lorenz curve to observed data. The two parameters ‘a’ and ‘b’ > characterizing the functional form of the Lorenz curve are expressed as > linear combinations of explanatory variables, say a = a0 + a1*X1 + a2*X2 and > b = b0 + b1*X1 + b2*X2. So what I really get from -nl- are the a`i's and > b`i's coefficients along with their associated std. err., t and p > statistics. > > Now, I want to compute a third parameter, the Gini coefficient ‘g’, which is > a non-linear combination of ‘a’ and ‘b’ involving the Beta function. What I > ultimately want to compute are the g`i's, that is, the coefficients > measuring the effects of the X`i's (including the constant) on ‘g’, with > their associated std. err., t and p. > > I know how to use -nlcom- to do so when only the constant term is involved > (nlcom g0: f(_b[/a0],_b[/b0])), but I couldn’t find how to deal with the > explanatory variables X. > > Any idea would be welcome ! > > Thanks in advance, > Regards, > Laurent > > -- > Laurent PIET > ---------- > INRA, UMR1302 INRA-Agrocampus > "Structures et Marchés Agricoles, Ressources, Territoires" > 4 allée Adolphe Bobierre | tél. : +33 (0)2.23.48.53.83 > CS 61103 | fax. : +33 (0)2.23.48.53.80 > F-35011 Rennes cedex | laurent.piet@rennes.inra.fr > ---------- > http://www.rennes.inra.fr/smart > > * > * 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: -nlcom- question***From:*Laurent Piet <Laurent.Piet@rennes.inra.fr>

**References**:**st: -nlcom- question***From:*Laurent Piet <Laurent.Piet@rennes.inra.fr>

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