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st: RE: Calculate confidence intervals for log-log models


From   Jason Ferris <[email protected]>
To   "'[email protected]'" <[email protected]>
Subject   st: RE: Calculate confidence intervals for log-log models
Date   Thu, 7 Mar 2013 22:46:47 +0000

Hello Paul,

Thank you for your solution.  That is perfect.

Kind regards,

Jason


Date: Wed, 6 Mar 2013 10:26:14 +0000
From: "Seed, Paul" <[email protected]>
Subject: st: RE: Calculate confidence intervals for log-log models

The same result can be got in a simpler way.

Consider a well-known example:
*********** Start of Stata code ***********
clear
sysuse auto
gen ln_price = ln(price)
gen ln_mpg = ln(mpg)

regress ln_mpg ln_price
* effect of a 10% increase in price on mpg.
lincom `=ln(1.1)'*ln_price , eform
* The mpg falls on average by 3.4% to 96.6% of the original value.

* Alternative method
nlcom 1.1^_b[ln_price]
* The same confidence interval; but the test (t in particular) 
* no longer agrees with that given by the regression. 


***********  End of Stata code  ***********



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