A 2 2 2 table satisfies i++ = +j+ = ++k =

A 2 × 2 × 2 table satisfies π_i++ = π_+j+ = π_++k = ½, all i, j, k. Give an example of {π_ijk} that satisfies model 

(a) (X, Y, Z), 

(b) (XY, Z), 

(c) (XY, YZ), 

(d) (XY, XZ, YZ), 

(e) (XYZ), but in each case not a simpler model.