Processes of normal inverse Gaussian type

With the aim of modelling key stylized features of observational series from finance and turbulence a number of stochastic processes with normal inverse Gaussian marginals and various types of dependence structures are discussed. Ornstein-Uhlenbeck type processes, superpositions of such processes and stochastic volatility models in one and more dimensions are considered in particular, and some discussion is given of the feasibility of making likelihood inference for these models.     

Intergenerational risk sharing and fiscal policy

Risk-sharing implications of alternative fiscal policies are compared in a stochastic production economy with overlapping generations. Ex ante efficiency is shown to be achievable with optimal transfers, regardless of distributional concerns. For CRRA preferences, stylized real-world policies (notably safe debt and safe pensions) are found inefficient in the direction of imposing not enough productivity risk on retirees and too much on future generations. Safe transfers can be rationalized as efficient if preferences display age-increasing risk aversion, such as habit formation. The ubiquity of safe transfers suggests that governments treat the young as more risk tolerant than older cohorts.     

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Ohne Zusammenfassung     

Nachhaltigkeit von Biokraftstoffen: Ziele,Probleme und Instrumente

Klimawandel und Versorgungssicherheit bestimmen die Suche nach ?kologisch und ?konomisch nachhaltigen Energietr?gern. Biokraftstoffe scheinen beiden Zielen gleicherma?en gerecht zu werden. Was ist bei der Bewertung der Nachhaltigkeit von Biokraftstoffen zu beachten? Sollte der Staat bei der Bereitstellung eingreifen? Welche wirtschaftspolitischen Instrumente schaffen positive Anreize beim Verbrauch von Biokraftstoffen? Dr. Michael Br?uninger, 43, ist Leiter des Kompetenzbereichs Wirtschaftliche Trends des Hamburgischen WeltWirtschaftsInstituts HWWI; Leon Leschus, 31, Dipl.-Volkswirt, und Dr. Henning V?pel, 35, sind dort wissenschaftliche Mitarbeiter.     

Understanding value-creating practices in social media-based brand communities

For service providers hosting social media-based brand communities, understanding the use of value-creating practices enables them to enhance their customers’ brand community experiences and facilitate value. Yet, extant social media-based brand community research neglects to examine the uses of practices in commonly occurring, direct service provider customer interactions that may be value co-creative. Thus, for a more holistic view of value creation, and informed by service logic, this study applies netnography to observe participants’ uses of practices in two social media-based cause brand communities, in both direct and indirect interactions. The findings reveal that participants predominantly employ practices in direct interactions and act as value co-creators. The findings extend empirical evidence into value-creating practices in social media-based brand communities. They also highlight how cause organisations should plan their uses of practices to facilitate the types of value-creating interactions they seek (i.e. direct and value co-creating, or indirect and independently value creating).     

Technological platforms An assessment of the primary types of technological platforms, their strategic issues and their linkages to organizational theory

The concept of a platform describes a set of system components that is strongly interdependent with most other system components, and that also co-determines the architecture of the system’s outcome. This concept underlies all kinds of technology-based products, collaborations that produce multi-product systems, and transactions between distinct sets of market participants. In this paper, I provide an overview of the growing scientific literature on technological platforms, and also identify three distinct, but related, literature streams: (1) product platforms; (2) industry platforms; and (3) two-sided markets. In doing so, I focus on empirical studies and mathematical models. For each stream, I then go on to describe the type of platform that the stream relates to, review the stream’s major studies (sorted by key strategic issues), and summarize and synthesize the overall findings before linking them to organizational theory and highlighting some potential gaps for future examination. In closing, I move to a comparison across streams and identify some currently unexplored aspects of the platform concept.     

Wie lässt sich die Dominanz der Finanzmärkte über die Politik lösen?

Der Krisenverlauf und die Bemühungen der Politik gegenzusteuern lassen den Eindruck entstehen, dass die Finanzm?rkte die Politik vor sich hertreiben. Die Politik hat offenbar durch ein Regulierungsversagen die Marktkr?fte nicht genügend geb?ndigt. Wurden die Kapitalm?rkte nicht schon seit langem von der Politik privilegiert? Welche konkreten Vorschl?ge gibt es, die Eurol?nder von den Finanzm?rkten unabh?ngiger zu machen? Welche Erfahrungen wurden in der Vergangenheit mit Verschuldungskrisen gemacht?