Bayesian Networks

16 Bayesian Networks: With Examples in R

where we denote the categories of Travel with t ∈ T, the categories of Edu-

cation with e ∈ E, and the configurations of Occupation and Residence with

k ∈ O × R. Hence, n

tek

is the number of observations for the combination of

a category t of Travel, a category e of Education and a category k of O × R.

The use of a "+" subscript denotes the sum over an index, as in the classic

book from Agresti (2013), and is used to indicate the marginal counts for the

remaining variables. So, for example, n

t+k

is the number of observations for t

and k obtained by summing over all the categories of Education. For Pearson’s

X

2

,