Managerial Incentive Problems: A Dynamic Perspective

The paper studies how a person's concern for a future career may influence his or her incentives to put in effort or make decisions on the job. In the model, the person's productive abilities are revealed over time through observations of performance. There are no explicit output-contingent contracts, but since the wage in each period is based on expected output and expected output depends on assessed ability, an "implicit contract" links today's performance to future wages. An incentive problem arises from the person's ability and desire to influence the learning process, and therefore the wage process, by taking unobserved actions that affect today's performance. The fundamental incongruity in preferences is between the individual's concern for human capital returns and the firm's concern for financial returns. The two need be only weakly related. It is shown that career motives can be beneficial as well as detrimental, depending on how well the two kinds of capital returns are aligned.     

不确定性条件下资本市场投资预期收益模型探析

在现实经济活动中特别是在资本市场投资中,人们对将来的情况很难准确地预测到,他们所知道的最多只不过是在未来各种各样的收益状况下所可能产生的结果.也就是说,未来经济活动特别是资本市场投资活动具有不确定性.由于不确定性的预期的作用和影响,在不确定性条件下的资本市场投资预期收益模型与在确定性条件下的收益模型存在着一定的偏差.只有减少人们对经济不确定性的预期,才能使资本市场投资需求旺盛.     

Innovation and stock market performance: A model with ambiguity-averse agents

Empirical evidence on stock prices shows that firms investing successfully in radical innovation experience higher stock returns. This paper provides a model that sheds light on the relationship between the degree of firm innovativeness and stock returns, the movements of which capture expectations on firm’s profitability and growth. The model is grounding on Neo-Schumpeterian growth models and relies on the crucial assumption of radical innovation, characterized by “ambiguity” or Knightian uncertainty: due to its uniqueness and originality, no distribution of probability can be reasonably associated with radical innovation success or failure. Different preferences (α-maxmin, Choquet) are here compared. Results show that the assumption of ambiguity-aversion is crucial in determining higher returns in the presence of radical innovation and that the specific definition of expected utility shapes the extent of the returns. This result holds also in the case of endogenous innovation; risk attitude plays no role.     

Organization Design and Information-Sharing in a Research Joint Venture with Spillovers

The paper presents a non-tournament model of process innovation with spillovers in the R&D process when firms engage in Cournot competition in the product market. It is shown that careful modelling of information-sharing and coordination of research activities leads to the conclusion that a Research Joint Venture (RJV) will economize on scarce R&D resources. There is an analysis of the effects of R&D cooperation, in the form of an RJV, on the organization of R&D, i.e. the efficient number of research labs. R&D expenditure, which precedes production, results in lower unit costs. R&D is modelled as a two-stage process: in the first stage, firms incur expenditure that will generate new knowledge, while in the second stage this knowledge is employed to reduce unit costs. A distinction is made between single and complementary research paths. It is shown that the RJV will operate one lab in the case of a single research path exploiting its coordination advantage. In the case of complementary research paths the number of labs the RJV will operate crucially depends on the stage of the R&D process at which diminishing returns occur: it will operate both labs when diminishing returns occur at the first stage (creation of knowledge), while it will be indifferent as to the number of labs, one or two, when diminishing returns occur in the second stage (cost reduction).     

收入差距与公共财政政策:人力资本投资差异的形成与演变

人力资本投资的需求受到经济个体的时间偏好、生产能力与预期收益率等因素的影响。同时,收入差距和公共财政政策都会影响到人力资本投资供给曲线的变动。这造成了不同个体之间在人力资本投资上的差异,产生了他们之间的人力资本差距和收入差距。我国现行的公共财政政策已经成为收入差距快速增长的重要原因。     

Human capital distribution, growth and convergence

This paper studies the dynamic relationship between distribution and endogenous growth in an overlapping generations model with accumulation of human and physical capital. It is shown how human capital can determine a relationship between per capita growth rates and inequality in the distribution of income. Family background effects and spillovers in the transmission of human capital generate dynamics in which aggregate variables depend not only on the stock, but also on the distribution of human capital. The evolution of this distribution over time is then characterized under different assumptions on private returns and the form of the externality in the technology for human capital. Conditions for existence, uniqueness and stability of a constant growth equilibrium with a stationary distribution are derived. Increasing returns, idiosyncratic abilities and the possibility of poverty traps are explicitely characterized in a closed form solution of the equilibrium dynamics, showing the role played by technology and preferences parameters.     

A Time-Varying Risk Analysis of Equity and Real Estate Markets in the US and Japan

The paper offers some new evidence which suggests that Japanese equity and real estate markets might not necessarily behave in a parallel manner to US capital markets. These results are obtained from an examination of the nature of expected and unexpected movements in the returns of Japanese assets and US assets using a present-value model which allows for a time-varying expected discount rate in conjunction with a VAR process. Based on data from 1972–92, it is found that one distinctive difference is that changes in the future expected return for Japanese real estate and stocks are less persistent over time than their US counterparts. It is also found that the impact of Japanese markets on the US market was relatively small. On the other hand, there is some evidence that the US equity market had some significant impact on the Japanese equity market. Returns on Japanese stocks also exhibit a weaker mean reversion process relative to returns on US stocks and US real estate.     

Status quo bias,multiple priors and uncertainty aversion

Motivated by the extensive evidence about the relevance of status quo bias both in experiments and in real markets, we study this phenomenon from a decision-theoretic prospective, focusing on the case of preferences under uncertainty. We develop an axiomatic framework that takes as a primitive the preferences of an agent for each possible status quo option, and provide a characterization according to which the agent considers a full-dimensional set of possible priors and abandons her status quo option only if she finds an alternative that returns a higher expected utility for each of these priors. We then show that, in this framework, the very presence of a status quo induces the agent to be more uncertainty averse than she would be without a status quo option.     

Dynamic asset allocation with ambiguous return predictability

We study an investor's optimal consumption and portfolio choice problem when he is confronted with two possibly misspecified submodels of stock returns: one with IID returns and the other with predictability. We adopt a generalized recursive ambiguity model to accommodate the investor's aversion to model uncertainty. The investor deals with specification doubts by slanting his beliefs about submodels of returns pessimistically, causing his investment strategy to be more conservative than the Bayesian strategy. Unlike in the Bayesian framework, the hedging demand against model uncertainty may cause the investor's stock allocation to decrease sharply given a small doubt of return predictability, even though the expected return according to the VAR model is large. Over much of the parameter space, the robust strategy is very close to the Bayesian strategy with Epstein–Zin preferences and risk aversion chosen to match the same average portfolio holdings. This is true in particular when the IID model is unlikely and the dividend yield is low, as in recent years. However, differences in strategies can be substantial if the IID model is unlikely and the dividend yield is high.     

Oil shocks,policy uncertainty and stock returns in China

This paper examines the interdependence of China's policy uncertainty, the global oil market and stock market returns in China. A structural VAR model is estimated that shows that a positive shock to economic policy uncertainty in China has a delayed negative effect on global oil production, real oil prices and real stock market returns. Shocks to oil market‐specific demand significantly raise China's economic policy uncertainty and reduce the real stock market returns. As measured by a spillover index, the interdependence between these variables has been rising since 2003 as China's influence in the oil market has increased. An equivalent spillover index calculated for the US is smaller and has been largely flat over time.     

POLITICAL CYCLES

A model of elections is put forth in which there are two parties, each representing a different constituency of voters (the poor and the rich). The political issue is the choice of a proportional tax rate on income, revenues from which are used to finance a public good. There is a stochastic element in which party wins the elections, due to party uncertainty concerning voter preferences, or due to uncertainty concerning which voters will show up at the polls. A political equilibrium in one period consists in a tax policy put forth by each party, and a probability that each party wins. A long series of elections is simulated (100 periods). Voter preferences for the public good change adversely as a function of length of time the incumbent party has been in power and the level of the public good in the last period. Thus, if the party in power funds high levels of the public good, preferences start to move against the public good. This model generates dramatic political cycles, and it is argued that these cycles are of fundamentally different origin from that discussed in the realignment literature.     

Interval portfolio selection models within the framework of uncertainty theory

The expected returns for securities are traditionally estimated as crisp values. Since the improper values may bring on an unsuccessful investment decision, portfolio experts generally prefer offering interval estimations for expected returns rather than crisp ones. The portfolio selection problem with interval expected returns is widely studied recently. In this paper, by considering the security returns with interval expected returns as uncertain variables, a mean-semiabsolute deviation model is proposed within the framework of uncertainty theory, which is a crisp nonlinear programming model and can be well solved by the classical optimization algorithms. In order to illustrate the method, some numerical experiments are given and solved.     

Policy Effects in Hyperbolic vs. Exponential Models of Consumption and Retirement

This paper constructs a structural retirement model with hyperbolic preferences and uses it to estimate the effect of several potential Social Security policy changes. Estimated effects of policies are compared using two models, one with hyperbolic preferences and one with standard exponential preferences. Sophisticated hyperbolic discounters may accumulate substantial amounts of wealth for retirement. We find it is frequently difficult to distinguish empirically between models with the two types of preferences on the basis of asset accumulation paths or consumption paths around the period of retirement. Simulations suggest that, despite the much higher initial time preference rate, individuals with hyperbolic preferences may actually value a real annuity more than individuals with exponential preferences who have accumulated roughly equal amounts of assets. This appears to be especially true for individuals with relatively high time preference rates or who have low assets for whatever reason. This affects the tradeoff between current benefits and future benefits on which many of the retirement incentives of the Social Security system rest.Simulations involving increasing the early entitlement age and increasing the delayed retirement credit do not show a great deal of difference whether exponential or hyperbolic preferences are used, but simulations for eliminating the earnings test show a non-trivially greater effect when exponential preferences are used.     

A SMOOTH AMBIGUITY MODEL OF THE COMPETITIVE FIRM

This paper examines the optimal production decision of the competitive firm under price uncertainty when the firm's preferences exhibit smooth ambiguity aversion. Ambiguity is modeled by a second‐order probability distribution that captures the firm's uncertainty about which of the subjective beliefs govern the price risk. Ambiguity preferences are modeled by the (second‐order) expectation of a concave transformation of the (first‐order) expected utility of profit conditional on each plausible subjective distribution of the price risk. Within this framework, we derive necessary and sufficient conditions under which the ambiguity‐averse firm optimally produces less in response either to the introduction of ambiguity or to greater ambiguity aversion when ambiguity prevails. In the case that the price risk is binary, we show that ambiguity and greater ambiguity aversion always adversely affect the firm's production decision.     

Fluctuations in convex models of endogenous growth, I: Growth effects

Is there a trade-off between fluctuations and growth? The empirical evidence is mixed, with some studies finding a positive relationship, while others find a negative one. Our objectives are to understand how fundamental uncertainty affects the long run growth rate and to identify important factors determining this relationship in a convex endogenous growth model. Qualitatively, we show that the relationship between volatility in fundamentals (or policies) and mean growth can be either positive or negative. The curvature of the utility function is a key parameter that determines the sign of the relationship. Quantitatively, an increase in uncertainty always increases the growth rate in our calibrated models. Though the changes we find are nontrivial, they are not large enough by themselves to account for the large differences in growth rates observed in the data. We also find that differences in the curvature of preferences have very substantial effects on the estimated variability of stationary objects like the consumption–output ratio and hours worked. For this reason, we expect that the models considered in this paper will provide the basis of sharp estimates of the curvature parameter.     

Career, experience and returns to human capital: is the dual labour market hypothesis relevant for the UK?

This paper investigates the relationship between career status, labour market experience and returns to human capital accumulation in the context of a two-tier, career and non-career labour market. Using micro data from the British Household Panel Survey (BHPS), this study detects wage and employment mechanisms that differ between these two tiers of workers. The paper finds no support for the hypothesis of strict duality, by which the returns to education are expected to differ across labour market segments, with the returns in career employment being high and positive and the returns in the non-career sector being close to zero. The paper, however, finds support for significant returns to current tenure only in the career sector and also for the scarring hypothesis, according to which part-time employment and unemployment experience have a negative effect on participation and earnings in the career sector. Finally, there is evidence that only non-career earnings are significantly affected by local demand conditions, in contrast to earnings in the career sector. Career status is modelled as an endogenous variable subject to an initial job choice.     

投资驱动型产业政策、地方固定资产投资与农村人力资本积累——基于中国家庭追踪调查(CFPS)的实证分析

基于中国家庭追踪调查（CFPS）2018年数据与笔者收集的数据,本文采用跨地区和出生队列的变异构造双重差分模型（Cohort DID）分析了地方政府投资驱动型产业政策对农村人力资本积累的影响。研究发现,2008年之后地方政府投资驱动型产业政策引致的大规模传统基础设施投资与农村适龄青年完成高中教育的可能性之间存在显著负相关关系。使用工具变量的检验结果表明,上述研究结论具有较强的稳健性。此外,本文还尝试性地探究了上述效应的作用机制：投资驱动型产业政策引致的传统基础设施投资大幅攀升,一方面增加了建筑业及相关低技能工作的机会,提升了投资教育的机会成本;另一方面带来了低技能劳动力工资的提升,导致了不同教育水平劳动力工资趋同、技能溢价下跌,降低了预期教育回报。本文的研究结论可以为“十四五”时期中国全面构建与创新驱动型经济发展模式相匹配的产业政策体系提供参考。     

Asset pricing in a production economy with Chew–Dekel preferences

In this paper we provide a thorough characterization of the asset returns implied by a simple general equilibrium production economy with Chew–Dekel risk preferences and convex capital adjustment costs. When households display levels of disappointment aversion consistent with the experimental evidence, a version of the model parameterized to match the volatility of output and consumption growth generates unconditional expected asset returns and price of risk in line with the historical data. For the model with Epstein–Zin preferences to generate similar statistics, the relative risk aversion coefficient needs to be about 55, two orders of magnitude higher than the available estimates. We argue that this is not surprising, given the limited risk imposed on agents by a reasonably calibrated stochastic growth model.     

Interim efficient allocations under uncertainty

This paper considers an exchange economy under uncertainty with asymmetric information. Uncertainty is represented by multiple priors and posteriors of agents who have either Bewley's incomplete preferences or Gilboa-Schmeidler's maximin expected utility preferences. The main results characterize interim efficient allocations under uncertainty; that is, they provide conditions on the sets of posteriors, thus implicitly on the way how agents update the sets of priors, for non-existence of a trade which makes all agents better off at any realization of private information. For agents with the incomplete preferences, the condition is necessary and sufficient, but for agents with the maximin expected utility preferences, the condition is sufficient only. A couple of necessary conditions for the latter case are provided.     

Dividend Variability and Stock Market Swings

This paper examines the extent to which swings in stock prices can be related to variations in the discounted value of expected future dividends when investors face uncertainty about their future behaviour. I develop an econometric model that accounts for the instability of U.S. dividend growth and discount rates during the past 120 years. Estimates of the model reveal that changing forecasts of future dividend growth account for more than 90% of the predictable variations in dividend-prices. The estimates also imply that instability in the dividend and discount rate processes contribute significantly to the predictability of long-horizon stock returns.