讲座主题：The Political Economy of Responses to COVID-19 in the U.S.A.
讲座提要：Social distancing via shelter-in-place (SIP) strategies and wearing masks have emerged as the most effective ways to combat COVID-19. In the United States, choices about these policies are made by individual states. Here we show that the policy choice made by one state influences the choices that other states make: these choices can be viewed as strategic complements in a supermodular game. If they satisfy the condition of uniform strict increasing differences then if enough states engage in social distancing or mask wearing, they will tip others to do the same and thus shift the Nash equilibrium. Political orientation is an important factor in determining a state’s willingness to implement mask-wearing or SIP strategies. We consider a situation where interactions amongst states are strongest between those of similar political orientations and show there can be equilibria where states with different politics adopt different strategies. In this case a group of states of one political orientation may by changing their choices tip others of the same orientation, but not those whose orientations differ. We test these ideas empirically using probit and logit models and find strong confirmation that states’ choices of SIP and mask-wearing policies are influenced by the actions of other states, and that equilibria can be tipped as the theory predicts. Policy choices appear to be influenced by the number of new COVID-19 cases in the state and the number of cumulative cases. The choice of mask-wearing policy shows more sensitivity to the actions of other states than the choice of SIP policies.