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From |
"Lachenbruch, Peter" <Peter.Lachenbruch@oregonstate.edu> |

To |
<statalist@hsphsun2.harvard.edu> |

Subject |
RE: st: Ask Non linear equation |

Date |
Fri, 15 Feb 2008 09:32:11 -0800 |

You may also wish to use the noconstant feature of regress. Next, you will want to estimate the variance of alpha2=gamma/alpha1 (I use gamma to mean the product of alpha1 and alpha2). This should be (using the delta method) var(gamma/alpha1)=var(gamma)/alpha1^2+var(alpha1)*gamma^2/alpha1^4-2cov( alpha1,gamma)*gamma/alpha1^3 Don't trust my math here - I derived this a couple of times with different answers... At any rate, you will need to access the returned matrices. Also, noconstant models have some tricky aspects that others may be better able to discuss. Tony Peter A. Lachenbruch Department of Public Health Oregon State University Corvallis, OR 97330 Phone: 541-737-3832 FAX: 541-737-4001 -----Original Message----- From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of David Greenberg Sent: Thursday, February 14, 2008 5:28 PM To: statalist@hsphsun2.harvard.edu Subject: Re: st: Ask Non linear equation The logarithm of a product is the sum of the logs of the individual factors. So you can rewrite this equation as log(Y) = alpha1 {log(X) + log[exp(alpha2*Z)]. In the second term, the log of the exponential is just alpha2*Z. So you can write this as log(Y) = alpha1 log(X) + alpha1*alpha2*Z. Define Y' = log(Y), X' = log(X), and you can estimate this as a linear equation. You can then recover alpha2 by dividing the estimated coefficient of Z by the estimated coefficient of X'. Or you can impose a constraint on the coefficients before doing the estimation. - David Greenberg, Sociology Department, New York University. ----- Original Message ----- From: adiwan fahlan <adiwan_f@yahoo.com> Date: Thursday, February 14, 2008 8:20 pm Subject: st: Ask Non linear equation To: statalist@hsphsun2.harvard.edu > Dear al > > my research in new economic geographic has demand an > advance > calculation. I want to ask about how to do this wage > equation : > > log (Y) = alpha1*log(X*exp(alpha2*Z)) > > Y is the dependent variable / wage > X and Z is the independent variable > and I have to find the coofiecient of alpha1 and > alpha2 > > According to the text book, its a nonlinear equation. > How can I program this equation in the non linear > programming? how to do that? or can I use nl command > that are already stored in STATA? > > I do really hope your help > > Thank you > > Regards > Adiwan > > > > > > ________________________________________________________________________ ____________ > Looking for last minute shopping deals? > Find them fast with Yahoo! Search. http://tools.search.yahoo.com/newsearch/category.php?category=shopping > * > * For searches and help try: > * http://www.stata.com/support/faqs/res/findit.html > * http://www.stata.com/support/statalist/faq > * http://www.ats.ucla.edu/stat/stata/ * * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/ * * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**References**:**st: _regress (stata9)***From:*"R.E. De Hoyos" <redeho@hotmail.com>

**st: Ask Non linear equation***From:*adiwan fahlan <adiwan_f@yahoo.com>

**Re: st: Ask Non linear equation***From:*David Greenberg <dg4@nyu.edu>

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