Consider three binary variables A,B,C. Using the vertical axis for Y and the horizontal axis for X, consider plotting the log odds for A given each...

Consider three binary variables A,B,C. Using the vertical axis for Y and the horizontal axis for X, consider plotting the log odds for A given each combination of Band C. Draw lines joining the pairs of points representing each level of C.

Prove be that there is homogeneous association among these variables if and only if the two lines are parallel.