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st: Re: rvfplot and heteroskedasticity


From   Christer Thrane <lineea@broadpark.no>
To   statalist@hsphsun2.harvard.edu
Subject   st: Re: rvfplot and heteroskedasticity
Date   Sun, 25 Nov 2007 09:58:31 +0100

Patricia wrote:

My estimation has heteroskedasticity problems. After
correcting the standard erros with -robust-, the graph
after -rvfplot- shows the same pattern. How can I see
the heteroskedasticity problem has been solved?
As far as I understand it, at least in the context of OLS regression, heteroskedasticity produces incorrect standard errors which in turn yield wrong t-statistics. -robust- solves the calculation of correct standard errors and therefore produce correct t-statstics, and not the heteroskedasticity itself.

If your dep var has many positive values, you might want to "log it" (gen newdep = LN(dep)) to reduce the amount of heteroskedasticity.

HTH

Christer


----- Original Message ----- From: "Celia Patricia Vera" <cpatriciavera@yahoo.com>
To: <statalist@hsphsun2.harvard.edu>
Sent: Sunday, November 25, 2007 7:20 AM
Subject: st: rvfplot and heteroskedasticity



Hi all,

My estimation has heteroskedasticity problems. After
correcting the standard erros with -robust-, the graph
after -rvfplot- shows the same pattern. How can I see
the heteroskedasticity problem has been solved?

Thanks for your attention,

Patricia.



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