--- On Tue, 12/1/10, Kaspar Dardas wrote:
> I have a question regarding the ",robust" option after
> runnig a multivariate regression. One of my independ variables is
> mcap (in Euros), which is often an extrem high number (some mcap
> numbers have more than twelve digits) compared to other numbers in
> my regression. Whenever I use the "robust" option the F-value
> drops in the result table and becomes blue.
<snip>
> However, if I run the exact same multivariate regression
> with mcap2 == mcap/100,000,000 and then use "robust". The F-value
> shows again.
<snip>
> Is this an appropriate method to "restore" the F-value?
Yes, dividing by a constant is just a linear transformation, so
they are just equivalent models. From a substantive point of view
an euro change in mcap is such a minute change that you don't care
about its effect, you would rather be interested in the change of
a million euro change in mcap. From a practical point of view, this
can make your model numerically more stable, as you experienced.
So it is a good thing whichever way you look at it.
Hope this helps,
Maarten
--------------------------
Maarten L. Buis
Institut fuer Soziologie
Universitaet Tuebingen
Wilhelmstrasse 36
72074 Tuebingen
Germany
http://www.maartenbuis.nl
--------------------------
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