Re: [Gretl-users] Heteroskedasticity / correction
When you multiply all the terms of the model by 1 / sqrt(x) the const of the original
model turns out to be
const / sqrt(x)
So this term of the corrected model is now a parameter (const) times a variable (1/
sqrt(x)) meaning that a 'const' alone disapeared in the new model.
Is this clear?
Sent from my iPhone
Apologize for the brevity/grammar/spelling
No dia 10/01/2014, às 21:26, Allin Cottrell <cottrell(a)wfu.edu> escreveu:
> On Fri, 10 Jan 2014, Ana Amaro ISG wrote:
>
> The test of this white Regression model does not have a constant...
> Right?
Right, and that was a bug, and it's now fixed in CVS and the
snapshots for Windows as OS X.
However, a puzzle remains: how are you arriving at the idea that the
constant "disappears" from the original model when you divide the
data by sqrt(x) to compensate for heteroskedasticity?
To get the adjusted constant you would do something like
series adjc = const / sqrt(x)
The result (adjc) will "disappear" (go to zero) only if the sqrt(x)
values are infinite, and I suppose it's safe to assume they are
actually finite.
Allin Cottrell
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