The expected value of a token sequence ab representing a PER when a is red and b is blue is: The expected value of the cases when the token pair ab is not a PER name is the sum of expected values of four cases: Table 2), which after simplification, is given by: The ratio between the cases when ab is a PER versus when ab is not a PER is: where the rationality values of tokens ab, a and b of being a PER, red ball or blue ball respectively.
the probabilities of a as a surname (red ball) and b as a first-name (blue ball) are:  The form of Equation (4) is similar to the concept of odds likelihood O(h), first introduced in Duda et al.