Behavior seminar

Du 07/09/2021 de 15:00 à 16:00

Online

ROEMER John (YALE)

Game-theoretic analyses of childhood vaccination behavior: Nash vs. Kant

Whether or not to vaccinate one's child is a decision that a parent may approach in several ways. The vaccination game, in which parents must choose whether or not to vaccinate a child against a disease, is one with positive alternalities (herd immunity). In some societies, not vaccinating is an increasingly prevalent behavior, due to deleterious side effects that parents believe may accompany vaccination. The standard game-theoretic approach is to assume that parents make decisions according to the Nash behavioral protocol, which is individualistic and non-cooperative. Because of the positive externality that each child’s vaccination creates for others, the Nash equilibrium suffers from the free-rider problem. However, in more solidaristic societies, parents may behave cooperatively -- they may optimize according to the Kantian protocol, in which the equilibrium is efficient. We test, on a sample of six countries, whether vaccination behavior conforms better to the individualistic or cooperative protocol. To do so, we conduct surveys of parents in these countries, to ascertain their beliefs about the subjective probability and severity of deleterious side effects of vaccination. Our analysis shows that in all the countries of our sample, the Kant model dominates the Nash model. We conjecture that, due to the free-rider problem inherent in the Nash equilibrium, social norms have developed, quite generally, inducing parents to vaccinate with higher probability than they would in the non-cooperative solution.