The impact of environmental regulation on productivity in German industries

The objective of this paper is to adjust a traditional total factor productivity (TFP) measure for the direct effect of environmental regulation on material and capital input. For this purpose we consider the fact that part of material input and pollution abatement capital have not been used to increase output but to cover the cost of using the environment as a factor of production. Therefore TFP growth rates are lower if part of the material input is allocated to abatement activities instead of producing output. We propose to treat compliance with environmental regulation as an unproductive input linked to the use of productive material input. Our aim is to answer and discuss two questions: How to measure the effect of environmental regulation on TFP, and does the effect matter. We examine data from 1975–1991 for ten pollution intensive German industries.We would like to thank Cornelia Oßwald for valuable research assistance. We are especially grateful to two anonymous referees for many helpful comments.     

Physical Search

Unidirectional search is an evolutionarily stable outcome in an economy where homogenous buyers and sellers can either move or stay. It is more efficient than bidirectional search. In unidirectional search, it is more efficient if the more numerous agents move and the less numerous agents stay, than vice versa.     

Von Neumann-Morgenstern stable sets, discounting, and Nash bargaining

We establish a link between von Neumann-Morgenstern stable set and the Nash solution in a general n-player utility set. The stable set-solution is defined with respect to a dominance relation: payoff vector u dominates v if one player prefers u even with one period delay. We show that a stable set exists and, if the utility set has a smooth surface, any stable set converges to the Nash bargaining solution when the length of the period goes to zero.     

Agglomeration in an innovative and differentiated industry with heterogeneous knowledge spillovers

This paper introduces an agent-based simulation model to study the technological development, the economic performance of firms and the evolution of agglomerations in a differentiated industry. The analysis is based on the interaction and behavior of firms, which might share knowledge but at the same time are competitors on the goods markets. Firms do not only compete with quantities they can also introduce process and product innovations. The level of knowledge of a firm describes the capabilities to perform innovations. Knowledge can be accumulated by investing in R&D and by knowledge spillover, which depend on geographical and technological proximity. Simulation runs show that there is an incentive to agglomerate in young industries and that geographical proximity enhances innovation, especially the number of product innovations.      

“Itô's Lemma” and the Bellman Equation for Poisson Processes: An Applied View

Using the Hamilton-Jacobi-Bellman equation, we derive both a Keynes-Ramsey rule and a closed form solution for an optimal consumption-investment problem with labor income. The utility function is unbounded and uncertainty stems from a Poisson process. Our results can be derived because of the proofs presented in the accompanying paper by Sennewald (2006). Additional examples are given which highlight the correct use of the Hamilton-Jacobi-Bellman equation and the change-of-variables formula (sometimes referred to as ``Itô's Lemma'') under Poisson uncertainty.     

Trees and decisions

Summary. The traditional model of sequential decision making, for instance, in extensive form games, is a tree. Most texts define a tree as a connected directed graph without loops and a distinguished node, called the root. But an abstract graph is not a domain for decision theory. Decision theory perceives of acts as functions from states to consequences. Sequential decisions, accordingly, get conceptualized by mappings from sets of states to sets of consequences. Thus, the question arises whether a natural definition of a tree can be given, where nodes are sets of states. We show that, indeed, trees can be defined as specific collections of sets. Without loss of generality the elements of these sets can be interpreted as representing plays. Therefore, the elements can serve as states and consequences at the same time.Received: 23 January 2003, Revised: 2 November 2003, JEL Classification Numbers: C72, D70. Correspondence to: Klaus RitzbergerWe are grateful to Larry Blume, Ariel Rubinstein, Jörgen Weibull, an anonymous referee, and seminar participants at the universities of Vienna, Salamanca, and Heidelberg for helpful comments. Financial support from the Austrian Science Fund (FWF) under project P15281 is also gratefully acknowledged.     

Technology management in the company of the future

This paper develops new conceptual ideas on the role of technology management in future companies. It draws consequences for their operatins, and it suggests new perspectives that arise from current trends in company development. It argues that technology management needs to address, in a differentiated manner, the problems which airse during the development process of companies and markets. Particular emphasis is placed on the demand of systems producers on technology management.     

Validity — the quest for reality in quantitative and qualitative research

It has been argued that fundamentally different methodological approaches have made for ‘two sociologies’. This view has obscured the fact that the problem of validity has to be tackled independently of any specific methodological premises because of the textuality of sociological data. This does not necessarily imply, however, a single, unified strategy for validity testing. In this paper, some basic theoretical presuppositions underlying the approach to validity testing in quantitative research will be contrasted with the strategies offered by Max Weber's methodological writings on the ideal type. It is argued that the use of ideal typical constructs in qualitative research (exemplified by patient's illness careers) allows systematic validity testing despite the important differences in the conceptualization of social reality which is used in quantitative research, thus serving the purpose of any empirical sociological research, that is, to gain valid insight into societies' concrete reality.     

Modelling cost complementarities in terms of joint production

Cost complementarities arise from synergies in the production of heterogeneous goods. It is shown that synergies can be accounted for in terms of shared public inputs (roughly) if and only if synergies decrease as the scope of production increases. This case of “substitutive” synergies is argued to be typical. The key technical tool is a novel interpretation of conjugate Moebius inversion in terms of higher-order differences.     

Family allowances as welfare improvements

The present paper studies the equilibria of a simple overlapping generations model of pure exchange in which money is traded. There is a continuum of agents in each generation and population growth is endogenous via voluntary decisions on children. Any monetary steady state has to satisfy the golden rule that the interest rate equals the growth rate. Still such a monetary steady state may be inefficient. If raising children is not excessively profitable, then there exists a transfer scheme, in favor of those who raise children, which improves upon the steady state.