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RE: st: manipulating matrix elements


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   "Nick Cox" <n.j.cox@durham.ac.uk>, <statalist@hsphsun2.harvard.edu>
Subject   RE: st: manipulating matrix elements
Date   Tue, 4 Apr 2006 17:59:15 +0100

The second paragraph applies when comparing 
matrices with the same number of cells
(#rows * #cols). Varying matrix size would
mess up the correlation. 

Nick 
n.j.cox@durham.ac.uk 

> -----Original Message-----
> From: Nick Cox 
> Sent: 02 April 2006 17:25
> To: 'statalist@hsphsun2.harvard.edu'
> Subject: RE: st: manipulating matrix elements
> 
> 
> That's not quite my point. 
> 
> In one case, the standardization is additive 
> and in the other it is multiplicative. 
> Either should leave the two measures 
> perfectly correlated, as a correlation is invariant 
> under a linear transformation, such as conversion
> from Fahrenheit to Celsius or vice versa. I trust the 
> failure to observe a correlation of 1
> is down to numerical fuzz. 
> 
> This still leaves the question of whether
> both standardizations are correct in different 
> senses, or whether they are the same, but 
> just appear superficially different. 
>  
> Otherwise put, suppose you are always 
> right on something, but my numbers are always 
> twice as big as yours. Our results
> are perfectly correlated but that doesn't 
> affect the fact that I am biased and
> therefore wrong. 
> 
> Nick 
> n.j.cox@durham.ac.uk 
> 
> Steve Vaisey
>  
> > I compared the standardizations (yours and Martin's) on a 
> > matrix of 11 
> > variables (for a total of 55 non-redundant, 2 variable 
> comparisons).  
> > They are highly correlated (~.99) so it's probably a matter 
> > of taste at 
> > one level.  Or am I missing something?
> > 
> > Thanks again for your help on this.
> > 
> > Steve
> > 
> > >

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