[LONGITUDINAL]
input={a, b, a1, a2, ry}
EQUATION:
f1 = a + b*t
f2 = a - b*t
DEFINITION:
y1 = {distribution=normal, prediction=f1, sd=a1}
y2 = {distribution=normal, prediction=f2, sd=a2}
;correlation = {r(y1, y2)=ry}
