The nature of the steady state in models of optimal growth under uncertainty

Summary. We study a one-sector stochastic optimal growth model with a representative agent. Utility is logarithmic and the production function is of the Cobb-Douglas form with capital exponent . Production is affected by a multiplicative shock taking one of two values with positive probabilities p and 1-p. It is well known that for this economy, optimal paths converge to a unique steady state, which is an invariant distribution. We are concerned with properties of this distribution. By using the theory of Iterated Function Systems, we are able to characterize such a distribution in terms of singularity versus absolute continuity as parameters and p change. We establish mutual singularity of the invariant distributions as p varies between 0 and 1 whenever . More delicate is the case . Singularity with respect to Lebesgue measure also appears for values such that . For and Peres and Solomyak (1998) have shown that the distribution is a.e. absolutely continuous. Characterization of the invariant distribution in the remaining cases is still an open question. The entire analysis is summarized through a bifurcation diagram, drawn in terms of pairs .Received: 9 April 2002, Revised: 29 October 2002, JEL Classification Numbers: C61, O41.Correspondence to: Tapan MitraThis research was partially supported by CNR (Italy) under the "Short-term mobility" program and by M.U.R.S.T. (Italy) National Group on "Nonlinear Dynamics and Stochastic Models in Economics and Finance" . We are indebted to Rabi Bhattacharya for providing us with the reference to Solomyak's (1995) paper. The present version has benefitted from comments by Mukul Majumdar and two anonymous referees.     

Trade and Renewable Resources in a Second Best World: An Overview

We provide an overview and introduction to the emerging field of trade and renewable resources, and discuss the potential impact of trade liberalization on welfare and resource conservation. A key factor determining the effect of trade reform is the institutional context or property rights regime, and our survey is organized such that it loosely follows the development of new insights with respect to institutions in this literature. This implies a transition from the benevolent planners model to the polar opposite benchmark of open access in the 1990s. Currently the pendulum is swinging back towards management and regulation, but institutions are treated as endogenous. We discuss and compare various key models in some detail and search for common ground between protagonists and antagonists of free trade. Paper based on Keynote address by Erwin Bulte, 12th Annual Conference of the European Association of Environmental and Resource Economists, Bilbao (Spain), June 28–30, 2003.     

Long memory in volatilities of German stock returns

We show that there is strong evidence of long-range dependence in the volatilities of several German stock returns. This will be done by applying a method using the difference of the classical log-periodogram regression estimator for the memory parameter and of the tapered periodogram based estimator. Both estimators give similar values for the memory parameter for each series and this indicates long memory. To support our findings we apply also a methodology using the sample variance and a wavelet based estimator to the data. Also these two methods show clear evidence of long-range dependence in the volatilities of German stock returns.First version received: December 2001/Final version received: March 2003The computational assistance of Eleni Mitropoulou and Björn Stollenwerck as well as the helpful comments of two unknown referees are gratefully acknowledged. Research supported by Deutsche Forschungsgemeinschaft under SFB 475. Stock returns were obtained from Deutsche Finanzdatenbank (DFDB), Karlsruhe.     

Earnings Differentials between State and Non-State Enterprises in Urban China

The present paper estimates earnings differentials between state and non-state sectors for Chinese urban residents in 1996 by taking into account differences in non-wage benefits. Household survey data are used to estimate wage differentials while aggregate statistics are utilised in estimating non-wage benefits. We find that state-sector workers earned significantly more than workers in urban collective and domestic private enterprises in 1996. Unskilled workers in foreign invested enterprises (FIE) earned significantly less than those in the state sector but skilled workers earned more in FIE than in the state sector. These findings shed light on the source of labour immobility that state-owned enterprise had experienced until recently.     

Reinterpreting the performance of immigrant wages from panel data

Immigrants differ from the native born in terms of unobserved factors, such as motivation, and observed factors, including those related to the interruption of labour market activity and earning capacity, which may bias estimates of immigrant integration. Using panel data from the Survey of Labour and Income Dynamics, we show that using potential experience, rather than actual experience, exaggerates estimates of the disruption and recovery caused by immigration. More importantly, we find support for omitted variables bias, arising from unobserved fixed effects. Instrumental variable estimates for both pooled and separate samples of immigrant and native born men demonstrate a wage disadvantage for immigrants upon entry that persists through their lifetime. Standard estimates of a modest wage advantage for the children of immigrants also suffer from omitted variables bias arising from unobservables. Contrary to most of the literature to date, our instrumental variable estimates which allow for unobservable fixed effects suggest that immigrants never catch up to otherwise comparable native born workers, but their children do just as well. We would like to thank Statistics Canada for permitting access to the data and solving associated technical problems, the Prairier Centre for Research on Immigration and Integration for financial assistance, and Peter Schnabl for excellent research assistance. An earlier version of this paper was presented to the 10th International Conference on Panel Data in Berlin, July 5–6, 2002. The authors take sole responsibility for errors, omissions and interpretation of the data.     

Enforcing Emissions Trading when Emissions Permits are Bankable

We propose enforcement strategies for emissions trading programs with bankable emissions permits that guarantee complete compliance with minimal enforcement costs. Our strategies emphasize imperfect monitoring supported by a high unit penalty for reporting violations, and tying this penalty directly to equilibrium permit prices. This approach is quite different from several existing enforcement strategies that emphasize high unit penalties for emissions in excess of permit holdings. Our analysis suggests that a high penalty for excess emissions cannot be used to conserve monitoring effort, and that it may actually increase the amount of monitoring necessary to maintain compliance.The authors are grateful to Anthony Heyes and three anonymous referees for their valuable comments. Partial support for this research was provided by the Cooperative State Research Extension, Education Service, U. S. Department of Agriculture, Massachusetts Agricultural Experiment Station under Project No. MAS00871.     

Efficiency wages and union-firm bargaining with private information

We consider efficiency wage effects in a union-firm bargaining model with private information. We show that an increase in the efficiency wage effects does not necessarily increase the wage level at equilibrium, even when the wage bargaining with private information is close to one with complete information. However, if it is commonly known that the firm is stronger than the union and the demand is sufficiently elastic, then an increase in the efficiency wage effects increases for sure the wage at equilibrium.JEL Classification: J41, J50, J52We thank Juan Dolado and two anonymous referees for valuable comments. Vincent Vannetelbosch is Chercheur Qualifié at the Fonds National de la Recherche Scientifique. The research of Ana Mauleon has been made possible by a fellowship of the Fonds Européen du Développement Economique Régional (FEDER). Financial support from the Belgian French Communitys program Action de Recherches Concertée 99/04-235 (IRES, Université catholique de Louvain) is gratefully acknowledged.     

论生态经济理论与科教兴农战略

融生态经济理论于科教兴农战略之中,以协调人与自然、经济与生态的关系,指导技术政策的制订和技术措施的选择以及科技兴农成果的评价,是中国式农业现代化的正确选择。     

生产函数与农史研究——评彭、黄大辩论

最近几年来,中国经济史研究中最轰动的大事就是美国加州大学的彭慕兰教授与黄宗智教授有关《大分流》一书的论争。①。细读双方争论的文章内容,可以发现,双方是历史学者,在讨论经济史时,对生产函数的概念与含苞欲放义并没有正确的理解。如果能够廓清一下,争论双方的逻辑可以变得更周严,双方之间的争论也许可以缓解一些。在此我只提三点,加以简述: (1)生产函数中边际产量下降的经济含义; (2)劳动生产力增加的泉源; (3 )边际产量之分析对中国小农的适用性。一　边际产量下降的含义黄宗智每次提到“内卷化”,总是写明定义是“劳动边际报酬…     

北京市下岗职工的再就业分析

该文利用独自收集到的有关北京市下岗职工的样本数据,分析了影响下岗职工失业持续时间的原因,探讨了影响下岗职工再就业前后收入变化的原因.通过分析得出以下主要结论:第一,下岗政策虽然在一定程度上促进了劳动力市场的形成,但随着下岗职工失业持续时间的延长,下岗政策已成为阻碍劳动力市场化的因素,同时也妨碍了市场经济体制下社会失业保障体制的建立和完善.第二,为了使更多的有在传统体制下工作经历的下岗职工,尤其是大量从事过企业管理工作的下岗职工尽快地实现再就业,不仅需要对他们进行各种技能的培训,而且更需要对他们进行如何适应新的经济环境的再教育.第三,"下岗"不仅是中国经济体制转型过程中的一个特殊时期的政策,实际上也是结构性失业在中国特有经济体制中表现出来的一种特有的现象.对于这种由于产业结构变化带来的失业问题,政府有必要制定更多的积极性的失业政策.