Strategic Certification and Provision of Quality

We study the effect of the presence of a certification intermediary in an environment where information asymmetries are particularly severe. The intermediary improves the information that buyers have about quality. This in turn increases the incentives that the seller has to provide high-quality goods. Efficiency is increased by the presence of the intermediary, but quality is underprovided in equilibrium relative to full information. The intermediary can implement the optimal policy in many ways. The amount of information revealed ranges from full disclosure to partial, noisy disclosure.     

Optimality conditions¶and bubbles in sequential economies¶and bounded relative risk-aversion

We provide specific qualifications in order that Kuhn–Tucker type Euler equations and transversality conditions at infinity hold in stochastic equilibrium models with heterogeneous agents and where assets are traded in sequential markets. It is not assumed that uncertainty is modeled as an event-tree structure or that preferences are necessarily bounded. We also describe an important class of preferences based on bounded relative risk aversion which yields relevant simplifications. Our results are used to establish conditions that rule out asset pricing bubbles. Specific examples of economies with bubbles are also discussed. Received: 28 January 2002 / Accepted: 19 July 2002 We are grateful to the editor and an anonymous referee for their valuable comments. This research was partially supported by MURST (Italy), National Group on “Nonlinear Dynamics and Stochastic Models in Economics and Finance”.     

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.     

Patents, Secrets, and the First-Inventor Defense

We analyze optimal patent design when innovators can rely on secrecy to protect their innovations. Secrecy has no fixed term but does not preclude accidental disclosure nor independent creation by other inventors. We derive the optimal scope of the rights conferred to such second inventors, showing that if the patent life is set optimally, second inventors should be allowed to patent and to exclude first inventors who have relied on secrecy. We then identify conditions under which it is socially desirable to increase patent life as much as is necessary to induce first inventors to patent. The circumstances in which it is preferable that they rely on secrecy seem rather limited .     

Small Leading Firms*

We formally analyze the question of whether a price leader must control a large share of the market. Our main result is that if other producers have rising marginal costs and behave as price takers, even the smallest firm in a competitive industry with a rising supply curve can enhance its profits by cutting output and raising price, becoming a price leader. Therefore, we would expect pure competition to be destroyed under these technological conditions.     

Multiple aspect testing for case-control designs

When testing for the equality of two distributions in a case-control design with treatment effects presumed to act possibly on more than one aspect, different tests may be properly considered for testing for different features of a null hypothesis, leading to the multiple aspect testing issue. Two different aspects are therefore of interest: the location-aspect, based on the comparison of location indexes, and the distributional-aspect, based on the comparison of the empirical distribution functions. A simulation study shows that the combined testing procedure exhibits a good robust overall performance, and an application in biomedical research is also presented.     

Do Institutions Cause Growth?

We revisit the debate over whether political institutions cause economic growth, or whether, alternatively, growth and human capital accumulation lead to institutional improvement. We find that most indicators of institutional quality used to establish the proposition that institutions cause growth are constructed to be conceptually unsuitable for that purpose. We also find that some of the instrumental variable techniques used in the literature are flawed. Basic OLS results, as well as a variety of additional evidence, suggest that (a) human capital is a more basic source of growth than are the institutions, (b) poor countries get out of poverty through good policies, often pursued by dictators, and (c) subsequently improve their political institutions.     

发展中国家的普遍服务政策

该文构建非对称信息模型分析普遍服务政策问题,其中政府对企业在农村提供服务的边际成本具有非对称信息.该文对区别定价和统一定价两种情形进行了对比分析.在实施区别定价时,不完全信息将提高农村地区的资费水平,并且降低相应的网络覆盖面积;而在实施统一定价时,农村地区的定价可能降低,但却是以网络覆盖的减少为代价的.该文的政策结论是:在实施普遍服务政策时,需要综合考虑网络投资的激励和用户承受能力.