19. Positive dependence. Two random variables (X, Y) with c.d.I, F(x, y) are said to be positively quadrant dependent if F(x, y) F(x, oo)F(oo , y) for all x, y .• For the case that (X, Y) takes on the four pairs of values (0,0), (0,1), (1,0), (1,1) with probabilities Poo, P01' P\O, Pl1'(X, Y) are positivelyquadrant dependent if and only if the odds ratio A= P01P\OlPooPl1 s 1.