Consider two models that you are to fit to a single data setinvolving three variables: A, B, and C.
Model 1 : A ~B
Model 2 : A ~B + C
(a) When should you say that Simpson’s Paradox is occuring?
A. When Model 2 has a lower R2 than Model 1.
B. When Model 1 has a lower R2 than Model 2.
C. When the coef. on B in Model 2 has the opposite sign to thecoef. on B in Model 1.
D. When the coef. on C in Model 2 has the opposite sign to thecoef. on B in Model 1.
(b) True or False: If B is uncorrelated with A, then thecoefficient on B in the model A ~ B must be zero.
(c) True or False: If B is uncorrelated with A, then thecoefficient on B in a model A ~ B+C must be zero.
(d) True or False: Simpson’s Paradox can occur if B isuncorrelated with C.
