R χ 2(s,t) (or R CV (s,t)) represents the similarity ranking of each translation candidate t with respect to s and is assigned to be from 1 to k (number of output) in decreasing order of similarity measure S X 2 direct (s,t) (or S CV direct (s,t)).
if the similarity rankings of t are high in both of the context-vector and chi-square methods, it will be also ranked high in the combined method.