摘要：We develop a tractable dynamic model of productivity growth and technology spillovers that is consistent with the emergence of real world empirical productivity distributions. Firms can improve productivity by engaging in in‐house research and developmenmt (R&D) or, alternatively, by trying to imitate other firms' technologies, subject to the limits of their absorptive capacities. The outcome of both strategies is stochastic. The choice between in‐house R&D and imitation is endogenous, and is based on firms' profit maximization motive. Firms closer to the technological frontier face fewer imitation opportunities, and choose in‐house R&D, while firms farther from the frontier try to imitate more productive technologies. The resulting balanced‐growth equilibrium features persistent productivity differences even when starting from ex ante identical firms. The long‐run productivity distribution can be described as a traveling wave with tails following a Pareto distribution as can be observed in the empirical data.
