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Re: st: Ask Non linear equation


From   David Greenberg <dg4@nyu.edu>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Ask Non linear equation
Date   Thu, 14 Feb 2008 20:28:27 -0500

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
> 
> 
>     
> 
> 
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