On 5 Feb 2002 18:01:15 -0800, [EMAIL PROTECTED] (Wuzzy) wrote:

> > You made a model with the "exact same exposure in different units",
> > which is something that no one would do, 
> 
> Hehe, translation is don't post messages until you've thought them
> through.
> 
> Anyway, turns out that the answer to my question is "No"..

Well, I think I speak for several statisticians when I say that
we still don't know what you refer to as 'multi collinearity'.  Do you
mean  100%, as in your question?   What *are*  you asking?

> Multicollinearity cannot force a correlation.  It turns out that ONE
> of the variables *was* correlated With R^2=0.45 and so
> multicollinearity had no effect on overall R^2.
 [ ... ]

If you are concluding that you won't improve R^2  by using
exactly the same variable twice, you are correct.  

Another post-er  has suggested where  you  *do*
have to watch out for multi-colliinearity:  He described the
case where the multiple R^2  is large despite small univariate 
correlations with the criterion.  (It was wordier than that, 
but that is what he did.)  

For further information-> You could search the last few months
of posts in sci.stat.*  using    groups.google.com   and look for
'confounding'  or  'masking';  and there might be something 
more in my own stats-faq.

-- 
Rich Ulrich, [EMAIL PROTECTED]
http://www.pitt.edu/~wpilib/index.html


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