small, smallA tax has a deadweight loss because it induces buyers and sellers to change their behavior. The tax raises the price paid by buyers, so they consume less. At the same time, the tax lowers the price received by sellers, so they produce less. Because of these changes in behavior, the equilibrium quantity in the market shrinks below the optimal quantity. The more responsive buyers and sellers are to changes in the price, the more the equilibrium quantity shrinks. Hence, the greater the elasticities of supply and demand, the greater the deadweight loss of a tax. So the policymaker should look for goods with as little elasticity as possible, in both supply and demand. See Section: The Determinants of the Deadweight Loss.