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From Al Chou <hotfusion...@yahoo.com>
Subject Re: [math] more improvement to storage free mean, variance computation
Date Sat, 14 Jun 2003 22:52:40 GMT
--- Phil Steitz <phil@steitz.com> wrote:
> Al Chou wrote:
> > --- Phil Steitz <phil@steitz.com> wrote:
> >>I think that is OK, since if you look at the definition of S earlier in 
> >>the paper, S is not the variance, it is the sum of the squared 
> >>deviations from the mean.  This should be always increasing.
> > 
> > 
> > Where is that definition?  I'm looking at equations 3 and 4, which define
> > S_{1,q} (in LaTeX notation), and the return statement in algorithm
> Procedure
> > var.2, which says S_{1,q} = S.
> 
> Equation 3 defines S to be the sum of squared differences between L_i 
> and L-bar, which are defined on p. 209 to be the observed values and 
> their mean.

Damn, you're right, sorry for being dense.  I wonder why they talk about
variance both before equation 3 and equation 5 and then don't bother to do the
final division that calculates it?  In any case, once I see whether my laptop
will boot stably, I'll put in the division by (i - 1) that turns S into the
variance and see how it goes.


Al

=====
Albert Davidson Chou

    Get answers to Mac questions at http://www.Mac-Mgrs.org/ .

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