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Re: st: AW: AW: Creating a variable taking the value of elasticity


From   Austin Nichols <austinnichols@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: AW: AW: Creating a variable taking the value of elasticity
Date   Tue, 8 Sep 2009 10:52:27 -0400

Dorothy Bridges<dbstata@gmail.com>:
The linear model and the log-log model make very different assumptions
about the data-generating process, so you should not expect to get the
same estimates from them.  -mfx- after a linear model in particular
will give approximate estimates that are very questionable--note that
if the true model is
y=Xb+e
then the elasticity of y with respect to x (a variable, or column of
X) will vary as x varies.

On Tue, Sep 8, 2009 at 10:32 AM, Dorothy Bridges<dbstata@gmail.com> wrote:
  I still
> don't see, then, how mfx, eyex gives me a value different than the
> coefficient on lnx in regress lny lnx.  Thanks again for all your
> thoughts.
>
>
> On Tue, Sep 8, 2009 at 10:20 AM, Maarten buis<maartenbuis@yahoo.co.uk> wrote:
>> --- On Tue, 8/9/09, Dorothy Bridges wrote:
>>> But what I don't understand is: the second method
>>> (using mfx, eyex) gives me a different value than
>>> the first method (storing the coefficient on x
>>> from *regress lny lnx*).  Why?

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