Stability under learning: The endogenous growth problem

A local dynamic analysis, in the neighborhood of the steady state, is developed for one and two-sector endogenous growth models. The problem differs from the conventionally assumed growth setups because one considers that expectations concerning the next period value of the control variable (consumption) are formed through adaptive learning. In such scenario, the found stability conditions reveal that convergence to the unique steady state point is feasible if a minimum requirement regarding the quality of learning in the long run equilibrium is fulfilled. Therefore, stability of growth under learning is dependent on the efficiency with which expectations are generated.     

Learning and international transmission of shocks

This paper studies the implications of adaptive learning in the modelling of inter-country linkages in a two-region MSG G-cubed model built on micro-founded behaviors of firms and households. The nature of the transmission process under rational expectations versus adaptive learning is explored. We investigate the propagation mechanism within and across borders for various shocks and policy changes within the United States: change in inflation target, fiscal policy, productivity shock, and rise in equity risk. Adaptive learning is found to change the short run sign of transmission in most cases but this also depends on the fraction of forward-looking agents in the economy.     

Selection dynamics and adaptive behavior without much information

This paper uses the experimental method to investigate behavior in a coordination game when the information available to subjects is limited to their feasible choices and their experienced payoffs. In the experiment subjects converge to an absorbing state at rates that are orders of magnitude faster than reinforcement learning algorithms, but slower than under complete information. This state is very close to a mutual best response outcome. All cohorts converged to the market statistic predicted by the interior equilibrium regardless of the information conditions or the stability conditions. Eric Battalio programmed the graphical user interface. The National Science Foundation and Texas Advanced Research Program provided financial support. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation or the Texas Advanced Research Program.     

A Markov analysis of social learning and adaptation

A number of recent contributions to the literature have modelled social learning and adaptation in an economic context. Understanding the processes driving these models is important in order to explain and predict the behaviour of the economy. In this paper, we analyze the economic applications for a class of adaptive learning models with bounded rational agents. The dynamics of these economies can be thought of as arising from discrete-time Markov chains. In particular, conditions for uniqueness of equilibria, convergence and stability in the economic systems follow from the accessibility and communication structures of these Markov chains. We establish a correspondence between absorbing states of the Markov chains and economic equilibria, whether stable or unstable, and develop theorems giving conditions for absorption and recurrence. Furthermore, we develop practical applications of these theorems using a cobweb model. We use a genetic algorithm, operating under election, as an example of a well known adaptive learning process.     

The overprovision anomaly of private public good supply

It is well known that private provision of a public good may lead to a higher supply than that in some Pareto optimal allocation. The traditional view attributes this overprovision anomaly to a specific kind of preferences. The present paper, however, shows that preferences do not play a decisive role. Assuming normality, overprovision will occur only if the distribution of income is extremely skewed and Pareto optimal allocations are not within the set of cost-share equilibria.     

Inequalities and fluctuations in a dynamic general equilibrium model

   Summary. In the present paper a tractable two-sector neo-classical growth model with heterogeneous agents is considered. The local dynamic properties of the equilibrium path are analyzed in relation with the underlying characteristics of the economy. In particular, the existence of fluctuations is related to the degree of heterogeneity in labor and in capital endowments. When applied to international trade theory, the analysis shows that free trade may distabilize a world economy that is originally stable under the regime of autarky. Received: December 28, 1998; revised version: October 29, 1999     

A costly state verification model with diversity of opinions

Summary. In simple models of borrowing and lending with ex-post asymmetric information, Gale and Hellwig (1985) and Williamson (1986) have shown that optimal debt contracts are simple debt contracts where borrowers repay a fixed interest rate whenever possible and lenders seize all the profit when borrowers default. In this note, we depart from their works by assuming that borrowers and lenders have heterogeneous beliefs, and show that simple debt contracts do not necessarily survive as optimal contracts.JEL Classification Numbers: G3, D8.     

Asset pricing with adaptive learning

We study the extent to which self-referential adaptive learning can explain stylized asset pricing facts in a general equilibrium framework. In particular, we analyze the effects of recursive least squares and constant gain algorithms in a production economy and a Lucas type endowment economy. We find that (a) recursive least squares learning has almost no effects on asset price behavior, since the algorithm converges relatively fast to rational expectations, (b) constant gain learning may contribute towards explaining the stock price and return volatility as well as the predictability of excess returns in the endowment economy but (c) in the production economy the effects of constant gain learning are mitigated by the persistence induced by capital accumulation. We conclude that in the context of these two commonly used models, standard linear self-referential learning does not resolve the asset pricing puzzles observed in the data.     

供给侧改革驱动下创新主体异质性与创新联盟关系风险

在供给侧改革驱动下,创新联盟因不同主体间可以共享资源、共担风险、降低创新成本而蓬勃发展。由于参与主体多元化、主体异质性特征客观存在、创新联盟成立之后关系风险逐步突出,理清影响关系风险的变量对创新联盟有效存续至关重要。从主体异质性理论出发,实证研究发现：创新主体异质性特征与创新联盟关系风险之间直接影响关系不显著,无论是互补性异质特征、制衡性异质特征还是互斥性异质特征都与关系风险的直接关系不显著。通过中介效应检验发现,主体异质性特征与创新联盟关系风险之间确实存在中介效应。权力非对称性是互补性异质特征与关系风险之间的中介变量;信任和信息共享是制衡性异质特征以及互斥性异质特征与关系风险之间的多重中介变量。探究了创新联盟主体异质性特征如何影响创新联盟关系风险,揭示了创新联盟关系风险管控的核心所在,可为创新联盟效率提升提供参考。     

Learning,large deviations and rare events

We examine the role of generalized stochastic gradient constant gain (SGCG) learning in generating large deviations of an endogenous variable from its rational expectations value. We show analytically that these large deviations can occur with a frequency associated with a fat-tailed distribution even though the model is driven by thin-tailed exogenous stochastic processes. We characterize these large deviations, driven by sequences of consistently low or consistently high shocks and then apply our model to the canonical asset pricing framework. We demonstrate that the tails of the stationary distribution of the price–dividend ratio will follow a power law.     

风险投资介入、投资策略与企业异质R&D创新——基于创业新兴指数样本公司的实证研究

利用创业新兴指数样本公司,实证考察了风险投资介入及其投资策略对企业异质研发创新的影响。结果表明:我国风险投资介入并未对企业异质研发创新产生显著影响;风险投资持股比重增大能显著促进公司常规式研发创新,而对探索式研发创新无显著促进效果;联合投资策略能够促进公司常规式研发创新,而对公司探索式研发创新的促进作用并不显著;单独投资策略对公司异质研发创新的促进作用不明显。这表明,我国风险投资对战略性新兴产业常规式创新具有一定的促进作用,但对探索式创新的促进效果不明显。     

和而不同：高管团队职能背景异质性对企业跨界技术并购绩效的影响

跨界技术并购能够为企业提供全新的创新思路,在技术融合与创新背景下,其优势易于发挥。在并购发生后,高管团队职能背景异质性在很大程度上作用于企业战略和创新决策,对企业发展具有至关重要的作用。因此,选取首次并购公告日在2007年1月1日到2016年12月31日间的73个跨界技术并购案例为样本,运用多元回归方法对高管团队职能背景异质性与企业跨界技术并购绩效的关系进行实证分析。结果显示,高管团队职能背景异质性对企业跨界技术并购绩效具有正向影响;市场化程度和可用冗余均正向调节上述作用。探索高管职能背景异质性对跨界技术并购绩效的作用机理,拓展信息决策理论应用情境,并为企业在跨界技术并购时进行高管团队配置和资源布局提供决策依据。     

One-way flow networks: the role of heterogeneity

I study a one-way flow connections model in which players are heterogeneous with respect to values and the costs of establishing a link. I show that values and costs heterogeneity are equally important in determining the level of connectedness and the architecture of equilibrium networks. I also show that when asymmetries are independent of the potential partner there are distributions of costs and values for which centrality is a distincitive feature of equilibrium networks. This sharply contrasts with the homogeneous case.I thank an anonymous referee for useful comments. The paper has benefited from discussion with Gabriella Conti, Jose Luis Moraga-Gonzalez, Fernando Vega-Redondo and Sanjeev Goyal.     

Expectations and learning under alternative monetary regimes: an experimental approach

Summary We design and analyze experimental versions of monetary overlapping generations economies under alternative policy regimes. Economies with a constant level of real deficit financed through seignorage, economies in which the level of deficit is adapted in order to follow a monetary policy with a target rate of inflation, and economies with preannounced changes in deficit levels are reported here. We also examine the behavior of an economy with no stationary competitive equilibrium. Our time series are compared to rational expectations equilibrium paths and to adaptive learning dynamics.Financial support for our work from the Graduate School of the University of Minnesota, the National Science Foundation (SES-8912552), Richard M. and Margaret Cyert Family Funds, and the Ministry of Education of Spain is gratefully acknowledged. We wish to thank Javier Diaz-Giménez, Jean Michael Grandmont, Robert Lucas, Albert Marcet, Charles Plott, Edward Prescott, Thomas Sargent, Neil Wallace and Michael Woodford for commenting on our work. We also thank Vijay Rajan for developing the software for the computerized experimental environment, and Jackie Cuccaro and Dhananjay Gode for their research assistance.     

Steady states in the OLG model with seignorage and long-lived agents

This note provides a direct proof of the fact that in a particular version of the overlapping generations model with long-lived agents and fiat money, there can be at most two stationary states. A simple argument showing the Pareto superiority of the low inflation steady state is also given.