On the interaction between risk sharing and capital accumulation in a stochastic OLG model with production

We analyze the interaction between risk sharing and capital accumulation in a stochastic OLG model with production. We give a complete characterization of interim Pareto optimal competitive equilibrium allocations. Furthermore, we provide tests of Pareto optimality/suboptimality based on (risky) rates of return only.     

Cost sharing with multiple technologies

We study cost sharing problems where gains from cooperation can come from the presence of other agents, such as when agents share their technologies. A simple model is built, where economies of scale are eliminated in order to study this effect. We use as the key axiom the property that, if an agent does not improve the technology of any coalition he joins, he should not get any part of the gain from cooperation. With properties of linearity and symmetry, this axiom characterizes a well-defined set of rules. From this set, we propose a rule derived from the familiar Shapley value. We show that it is the only rule in that set satisfying an upper-limit property on individual cost allocations or a monotonicity property when technology improves. We also derive a distinct rule using a property that ensures that no coalition has an incentive to manipulate the individual demands of its members.     

Cost sharing with multiple technologies

We study cost sharing problems where gains from cooperation can come from the presence of other agents, such as when agents share their technologies. A simple model is built, where economies of scale are eliminated in order to study this effect. We use as the key axiom the property that, if an agent does not improve the technology of any coalition he joins, he should not get any part of the gain from cooperation. With properties of linearity and symmetry, this axiom characterizes a well-defined set of rules. From this set, we propose a rule derived from the familiar Shapley value. We show that it is the only rule in that set satisfying an upper-limit property on individual cost allocations or a monotonicity property when technology improves. We also derive a distinct rule using a property that ensures that no coalition has an incentive to manipulate the individual demands of its members.     

Optimal risk sharing with background risk

This paper examines qualitative properties of efficient insurance contracts in the presence of background risk. In order to get results for all strictly risk-averse expected utility maximizers, the concept of “stochastic increasingness” is used. Different assumptions on the stochastic dependence between the insurable and uninsurable risk lead to different qualitative properties of the efficient contracts. The new results obtained under hypotheses of dependent risks are compared to classical results in the absence of background risk or to the case of independent risks. The theory is further generalized to nonexpected utility maximizers.     

Cycles in basic innovations

Basic innovations are believed to be one of the drivers of economic growth. In this paper we examine if cycle periods found for economic data correspond with cycles in basic innovations. For an annual time series of count data on innovations covering 1764-1976, we fit a harmonic Poisson regression model. We find the presence of multiple cycles with periods 5, 13, 24, 34 and 61, and these show a remarkable resemblance with commonly found economic cycles.     

Cost information sharing with uncertainty averse firms

Summary. A homogeneous Cournot duopoly with asymmetric information is analyzed. Every firm learns its own marginal cost parameter, but not the marginal cost parameter of the opponent. Every firm can commit to revealing its private information to the other firm, i.e. to share information. The influence of uncertainty aversion on the readiness of the duopolists to share cost information is analyzed. Uncertainty aversion is modeled according to the Choquet utility theory. It is shown that low uncertainty aversion leads the firms to share information, while high uncertainty aversion leads the firms not to share. A simple economic explanation for this result is given.Received: 5 January 2001, Revised: 7 May 2003, JEL Classification Numbers: D43, D81, D82.I wish to thank Jürgen Eichberger, Volker Krätschmer, Willy Spanjers, seminar participants at Universität des Saarlandes, seminar participants at University College London, participants in the conference of the Verein für Socialpolitik in Mainz 1999 and an anonymous referee for helpful comments. The views expressed in this paper are those of the author and do not necessarily reflect the views of the European Central Bank.     

Patent law and complementary innovations

This paper explores which patent policy should be applied to complementary innovations that are aggregated into broader technologies. I compare a setting in which complementary innovations must be bundled prior to patenting, with a second setting in which they can be patented separately. The first setting can improve static efficiency by avoiding the costs resulting from the scattering of complementary patents. But it also limits the disclosure of small innovations, which may lead to inefficient R&D cost duplications. A model capturing these effects shows that patenting complementary innovations separately is not efficient when innovations can be developed rapidly. This result justifies the enforcement of a severe “inventive step” or “non-obviousness” requirement in sectors where complementary innovations are frequent.     

Inter-firm diffusion of process innovations

This paper introduces a model of the diffusion of process innovations. It predicts that the inter- firm diffusion curve, showing the proportion of firms having adopted a given innovation, will follow either a cumulative normal time path for major and technically complex innovations or a cumulative lognormal time path for simpler and less expensive innovations. This prediction is tested, with satisfactory results, against data on the diffusion of various innovations in the U.K. The model also provides a limited explanation of why some firms adopt faster than others and identifies a number of factors which will determine the aggregate speed of diffusion.     

The political reception of innovations

Why do some societies embrace innovative technologies, policies, and ideas, while others are slow to adopt, and some even resist, them? Incumbent producers are most likely to be affected by certain kinds of innovations; they also wield a disproportionate influence in the design of institutions and policies that encourage or limit their adoption. We show formally that the elite has four cardinal policy options: to appropriate the innovation for itself; to encourage its adoption; to tax, regulate, or limit the innovation; or to block it. We show that six features of an innovation determine how it is received: (i) whether it is easy to replicate; (ii) whether it complements or competes with the elite's sources of income; (iii) whether its impact is broad or narrow; (iv) whether it is location-dependent, and (v) concealable; (vi) whether it requires large fixed costs. While other works have occasionally considered one of these factors, we show where each feature comes from, and we assess them systematically and together. We provide illustrative evidence of the relevance and generality of the model to understand the fate of a variety of innovations.     

Full versus quasi MLE for ARMA-GARCH models with infinitely divisible innovations

We compare the backtesting performance of ARMA-GARCH models with the most common types of infinitely divisible innovations, fit with both full maximum likelihood estimation (MLE) and quasi maximum likelihood estimation (QMLE). The innovation types considered are the Gaussian, Student’s t, α-stable, classical tempered stable (CTS), normal tempered stable (NTS) and generalized hyperbolic (GH) distributions. In calm periods of decreasing volatility, MLE and QMLE produce near identical performance in forecasting value-at-risk (VaR) and conditional value-at-risk (CVaR). In more volatile periods, QMLE can actually produce superior performance for CTS, NTS and α-stable innovations. While the t-ARMA-GARCH model has the fewest number of VaR violations, rejections by the Kupeic and Berkowitz tests suggest excessively large forecasted losses. The α-stable, CTS and NTS innovations compare favourably, with the latter two also allowing for option pricing under a single market model.     

The revitalization of Northeast China economy must start with institutional innovations

Starting with the basic knowledge of the system, the researcher analyzes the significance of institutional innovation in revitalizing old industrial bases in Northeast of China. It is not difficult to discover that Northeast＇s backwardness is caused by both of the historical and the artificial reasons. What＇s more, owing to the establishment of market economy, the old system no longer satisfies the development of the new system. Therefore, in order to speed up the Northeast region＇s economy and make it truly become the fourth growth pole, we must accelerate the innovation system.     

Optimal stopping time with stochastic volatility

This paper demonstrates how to convert a path-dependent optimal stopping time problem into a path-independent problem using a transformation analysis method. We test this method to deal with several problems, especially those in stochastic volatility environments. We introduce stochastic state variables into volatility dynamics and analyse the influence of state-variable volatile characters on investment stopping boundaries. For arbitrary coefficient circumstances, we set up a Riccati equation that satisfies the transformation. For circumstances involving Heston stochastic-volatility, we propose an analytical solution. This paper extends research on the optimal investment stopping issue to a stochastic investment opportunity environment. Our proposed method can enhance the ability of optimal investment stopping theory to describe the real capital market.     

Pensions with endogenous and stochastic fertility

This paper studies the design of a pay-as-you-go social security system in an overlapping generations model where fertility is in part stochastic and in part determined through capital investment. If investments are publicly observable, pension benefits must be linked positively to the level of investment, and payroll taxes negatively to the number of children. The outcome is characterized by full insurance with all parents, regardless of their number of children, enjoying identical consumption levels. Without observability, benefits must increase, and payroll taxes decrease, with the number of children. The second-best level of investment, and the resulting average fertility rate, are less than their corresponding first-best levels.     

Risk sharing and export performance with firm heterogeneity

We investigate how market uncertainty affects the export performance of a firm through financial frictions. We first extend Melitz's (2003) heterogeneous firm trade model by incorporating demand shocks, linking the demand uncertainties to the financing costs of firms. In this extension, the default probability is endogenously determined by a firm's productivity and demand uncertainty. Hence, firms with higher productivity or lower market uncertainty are offered lower interest rates and thus show better export performance. As an application, we also show that a risk-sharing mechanism, that pools default risk for a certain group of firms, lowers the default risk. This mechanism allows banks to charge lower interest rates to the member firms and therefore ultimately improves their export performance in both extensive and intensive margins. We find a real-world example of such a mechanism from business groups in Korea. Using Korean firm-level data, we show that the more diversified the business group, the greater the likelihood that its member firms export and the bigger their export revenues. We also show that our results are robust to alternative explanations for Korean business groups’ export competitiveness.     

Testing separate models with stochastic regressors

In this paper we generalize the R procedure to test a null linear regression model against a separate alternative in the context of generalized instrumental variable estimation, and thereby motivate the use of the standard F test. The relations between the F test and several one-degree-of-freedom separate tests are examined under the null, and the asymptotic distributions of the statistics are evaluated under local alternatives. It is shown that the one-degree-of-freedom tests can be more powerful than the F test under a Pesaran-type local alternative, and that the F test is more widely consistent than the one-degree-of-freedom tests.     

Intergenerational redistribution and risk sharing with changing longevity

Trend increases in longevity are a global phenomenon challenging the fiscal sustainability of current welfare arrangements. Policy proposals abound and often build on implicit assertions concerning intergenerational equity. This paper offers a simple but manageable OLG model with endogenous retirement and cohort-specific longevity to address intergenerational redistribution and risk sharing. While it is well known that a utilitarian planner strives for consumption smoothing, it is shown that healthy ageing calls for work smoothing in the sense that retirement ages increase with longevity. Hence, cohorts with higher longevity should contribute to their larger consumption needs via later retirement, although it is shown that the planner still front-loads some financing (pre-saving). Stochastic longevity raises the issue of intergenerational risk sharing, which implies that cohorts turning out to have a high longevity are compensated at the expense of cohorts turning out to have a relatively short longevity.     

Optimal production of innovations under uncertainty

The paper reports results on a risk-neutral firm's research incentives. When unrelated to the firm's own stake in the program, the risks encourage or discourage risky research spending, depending on the properties of the research technology available. A non-decreasing time path of information builds the idea of an asymmetric probability distribution of the state of knowledge into the model. It follows that the required return on risky investments may actually fall short of the safe return. Since it is the upside risk that dominates, increased controllable risks will increase incentives for risky innovative activity. It is proved, but only in a more restricted framework (with differentiable processes), that the expectational effects involved will strengthen the positive relationship between controllable risks and the expected return.I am greatly indebted to three anonymous referees for helpful suggestions and to the Yrjö Jahnsson Foundation for financial support.     

Financial innovations and managerial incentive contracting

Abstract.  The top executives' demands for financial instruments that enable them to hedge the risk exposure in their compensation has increased drastically in the last decade. We analyse the implications of a manager's hedging ability for effort incentives. We show that if the manager's hedging opportunity is limited to a known fixed number of trading rounds with risk‐neutral third parties, then the equilibrium effort is not affected at all. If the manager has the opportunity to hedge without committing to a last trading round, however, she hedges completely and no effort incentives can be sustained. Therefore, limiting the manager's opportunity to hedge to a fixed known number of trading rounds is crucial for sustaining incentives. JEL classification: G30, G32     

Multiple method forecasts for discontinuous innovations

This paper argues for the development of more explicit forecasting methodologies that use the pragmatics of combining methods and the philosophical base of multiple perspectives. The increasingly common “wicked” problem of forecasting demand for discontinuous innovations (DI) at the concept testing stage of new product development is used to ground the discussion. We look to the interpretivist group-based inquiry methodologies in the management and information systems literature, and coupled this with discussions with forecasting managers, to provide evidence to support the adoption of this approach. Relativism is briefly critiqued and the accuracy of the combining methods forecasting literature reviewed. It appears that the managers interviewed could benefit from an explicit understanding of the multiple perspective approach, as they already appeared to have appreciated the need for a broader based approach than traditional forecasting techniques. It is therefore hoped that as a result of this paper, more managers involved with the “wicked” problem of innovative product forecasting will recognise the need to adopt a more explicit multiple perspective inquiry methodology in their efforts to combine forecasting methods.     

Endogenous innovations in the pharmaceutical industry

This paper addresses the creation of new products in the US pharmaceutical sector, during the second half of the 20th century. We indicate that the continuous increases in population, and thus in the market size of this sector, play a fundamental role in explaining the large creation of new drugs during that period. We also argue that population and market size can be endogenously determined through the impact of drugs over the mortality rate. Hence, these two effects reinforce each other, producing decrements in the mortality rate and increments in the stock of drugs over time. We obtained the set of new molecular entities approved by the FDA during the second half of the 20th century and we decomposed the data in a panel of 15 therapeutic categories over time. Using this data, we tested our hypotheses using different econometric methods. The results support the hypothesis and are consistent across methods.