Chi Squared in Face Recognition

Andrew writes the following formula for X^2

Based on the definition of Chi squared:

Shouldn’t it be:
( f(x1)k-f(x2)k )^2 / ( f(x(2)k) )

Hi Jaskeerat,

The weighted chi square is used. See

On the statistics of the weighted chi square see Cohen, J. (1972). Weighted chi square: An extension of the kappa method. Educational and Psychological Measurement, 32, 61-74.

Aah, thanks for the reference!