Christopher Harris, Philip Reny, Arthur Robson, The Existence of Subgame-Perfect Equilibrium in Continuous Games with Almost Perfect Information: A Case for Public Randomization, Econometrica, Vol. 63, No. 3 (May, 1995), pp. 507-544

The authors introduce a dynamic and fully strategic model of wage determination in the presence of firm-specific human capital. In this model, human capital is interpreted as information. The authors show that equilibrium exists and is efficient and that it gives rise to a unique distribution of the social surplus. They show further that the equilibrium wage is determined by three factors. Consideration of these factors allows the authors to determine when and how the market mechanism enables the worker to capture some of the returns to firm-specific human capital. They relate their findings to the ongoing empirical debate concerning the return to tenure. Copyright 1996 by University of Chicago Press.

Is more intense product market competition and imitation good or bad for growth? This question is addressed in the context of an endogenous growth model with “step-by-step” innovations, in which technological laggards must first catch up with the leading-edge technology before battling for technological leadership in the future. In contrast to earlier Schumpeterian models in which innovations are always made by outsider firms who earn no rents if they fail to innovate and become monopolies if they do innovate, here we find: first, that the usual Schumpeterian effect of more intense product market competition (PMC) is almost always outweighed by the increased incentive for firms to innovate in order to escape competition, so that PMC has a positive effect on growth; second, that a little imitation is almost always growth-enhancing, as it promotes more frequent neck-and-neck competition, but too much imitation is unambiguously growth-reducing. The model thus points to complementary roles for competition (anti-trust) policy and patent policy.

OPTIMAL LEARNING BY EXPERIMENTATIONThis paper analyses the dynamic decision problem of an agent who is initially uncertain as to the true shape of his payoff function, but who obtains information aboutit over time by observing the outcome of his past decisions.In the long run, the action is a short run optimum given the beliefs, but may not be an optimum for the true payoff function.We derive conditions under which the limit action is optimal for the true payoff function and establish the robustness of the results.Finally we study the adjustment process in an example where such complete learning does not achieve in the long run.

We study the socially optimal level of illiquidity in an economy populated by households with taste shocks and present bias with naive beliefs. The government chooses mandatory contributions to accounts, each with a different pre-retirement withdrawal penalty. Collected penalties are rebated lump sum. When households have homogeneous present bias, β, the social optimum is well approximated by a single account with an early-withdrawal penalty of 1−β. When households have heterogeneous present bias, the social optimum is well approximated by a two-account system: (i) an account that is completely liquid and (ii) an account that is completely illiquid until retirement.