Re: Use of G Statistics equation for comparing sample distribution.

On Jun 18, 1:29 pm, crd...@xxxxxxxxx wrote:
I am working on a project which involves comparing two regions of an
image by means of a "G statistic"  The equation I am to use is as
follows:

E_(variable) denotes a Sigma (Summation) with variable as its
condition

ie:
-------
\
/
-------
variable

s,m are two histograms (256x8 2D histograms)
i is a bin number
f_i is the frequency at bin i

The equation, as defined in the paper I'm using, is:

G = 2*( [E_s,m E_i f_i log f_i] -[E_s,m (E_i f_i) log (E_i f_i)] -
[E_i (E_s,m f_i) log (E_s,m f_i) ] +
[(E_s,m E_i f_i) log (E_s,m E_i f_i) ]

I am trying to perform this comparison within a computer program but I
am unsure of the logical flow of it, mostly since there are 3
variables (s,m,i) but only one is explicitly shown to be used.  I am
not familiar with this complex of a problem so if anyone could help my
try and decipher this equation, I would be grateful.

Chris

Chris,
You are not getting answers because we can't understand what's going
on. I think you'll need to clarify the setup and the notations (and
perhaps answer your question along the way). It is not clear what the
indices s and m represent. What is a 2D histogram? Does it mean that
you have two binned variables, and you have a count for each pair of
bins? Does s run along one dimension and m along the other, or perhaps
i runs along the entire 2D space? And you have two of those?

Aniko
.

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