where M denotes medical care demand, measured by physician visits and emergency room visits; Info indicates consumer health information searching behavior; Ltrust is a binary variable measuring the degree of patients’ distrust in physicians; X is a vector of exogenous observable individual characteristics and county-level physician characteristics; ε is the disturbance term. Demeaned Ltrust is used to interact with Info, so that the coefficient, ˇ2, on the interaction can reflect the substitution effect of consumer health information on medical care use, while the coefficient ˇ1 on Info indicates the average effect. As per the conceptual discussion, we expect that ˇ1 > 0 and ˇ2 < 0.