Asset allocation in markets with contagion: The interplay between volatilities,jump intensities,and correlations

We study the impact of financial contagion on the dynamic asset allocation problem of a CRRA investor facing an incomplete market with two risky assets. We apply a Markov chain regime-switching framework with state-dependent jump intensities, diffusion volatilities and diffusion correlations. The key model feature that a switch to the bad contagion regime is triggered by a loss in one of the risky assets allows for the implementation of a hedging demand against contagion risk. Moreover, a state-dependent diffusion correlation combined with heterogeneity in jump intensities and volatilities can, e.g., generate a flight to quality effect upon a systemic jump.     

Gene-environment interactions and the complexity of human genetic diseases

In the assessment of mortality and morbidity risk, the ability of family history and genetic test results to predict the age of occurrence, severity, and long-term prognosis of 'genetic' diseases is important. An increasing number of gene-gene and gene-environment interactions have been demonstrated in a number of monogenic Mendelian diseases. These interactions can significantly modify the clinical presentation (disease phenotype) of diseases previously regarded purely as 'genetic.' As a result, 'genetic' diseases can be positioned in a continuum between classic Mendelian and complex disease where the extremes, pure genetic or solely non-genetic, do not exist. The position of any given disease in this continuum is defined by three components: the major gene(s) contributing to the phenotype, the variability added by modifier genes and the significance of environmental factors influencing the phenotype. As the predictive value of genetic test results can be significantly influenced by additional genetic and environmental risk factors, a better understanding of these factors may influence the quantification of mortality and morbidity risk.     

Interaktivität, Interaktion, Internet

In recent years, numerous suggestions have been made to clarify the concept of interactivity in communication science. Most often, an inclusion strategy is used, in which diverse definitions are summarized into a multi-dimensional notion of interactivity. Aside from this, there is also an exclusion strategy: On the one hand, certain technical media (computer-mediated communication, »interactive television«) or communicative situations (face-to-face communication) are marked as »interactive«. In doing this, no differentiation is made between potential and process, and betwen »interactivity« and »interaction«. On the other hand, the notion of interaction as it is rooted in sociology offers itself for a theoretically grounded definition. Seven ways of using the term in relationsship to the notion of communication can be found. It is suggested to conceptualize interaction as a type of communication in the sense of Rafaeli: Interactive communication is reciprocal and relates to earlier messages. The concept of interactive communication chosen here can be linked with systems theory and the deliberative theory of the public sphere.     

Attitudes Toward Catastrophe

In light of climate change and other global threats, policy commentators sometimes urge that society should be more concerned about catastrophes. This paper reflects on what society’s attitude toward low-probability, high-impact events is, or should be. We first argue that catastrophe risk can be conceived of as a spread in the distribution of losses. Based on this conception, we review studies from decision sciences, psychology, and behavioral economics that explore people’s attitudes toward various social risks. Contray to popular belief, we find more evidence against than in favor of catastrophe aversion—the preference for a mean-preserving contraction of the loss distribution—and discuss a number of possible behavioral explanations. Next, we turn to social choice theory and examine how various social welfare functions handle catastrophe risk. We explain why catastrophe aversion may be in conflict with equity concerns and other-regarding preferences. Finally, we discuss current approaches to evaluate and regulate catastrophe risk.     

Dictator games: a meta study

Over the last 25 years, more than a hundred dictator game experiments have been published. This meta study summarises the evidence. Exploiting the fact that most experiments had to fix parameters they did not intend to test, in multiple regression the meta study is able to assess the effect of single manipulations, controlling for a host of alternative explanatory factors. The resulting rich dataset also provides a testbed for comparing alternative specifications of the statistical model for analysing dictator game data. It shows how Tobit models (assuming that dictators would even want to take money) and hurdle models (assuming that the decision to give a positive amount is separate from the choice of amount, conditional on giving) provide additional insights.     

Measuring the immeasurable — A survey of sustainability indices

Sustainability indices for countries provide a one-dimensional metric to valuate country-specific information on the three dimensions of sustainable development: economic, environmental, and social conditions. At the policy level, they suggest an unambiguous yardstick against which a country's development can be measured and even a cross-country comparison can be performed. This article reviews the explanatory power of various sustainability indices applied in policy practice. We show that these indices fail to fulfill fundamental scientific requirements making them rather useless if not misleading with respect to policy advice.     

Collaboration,motivation, and the size of organizations

We present an analytical model of an organization that offers operational drivers of limits on team size. The model trades off benefits from collaborative problem solving against the disadvantages of diminishing motivation when groups get large. Collaboration is represented as parallel employee activity combined with frequent sharing of partial information, with a resulting superlinear performance increase over team size. Motivation is modeled by team members periodically setting an effort level either to contribute to the best of their ability or to “cruise”; at the minimum level not recognizable as shirking. Each individual decision is limited by bounded rationality based on team rewards, the time horizon of team interaction, and individual expectations about colleagues’ behavior. The decision collapses to a simple “barrier rule”;. Work hard when a certain “barrier percentage”; of team members work hard, and otherwise shirk. The influence of team size on this barrier percentage depends on the extent of benefits from collaboration: As long as performance increases quadratically with team size, the increased benefits resulting from collaboration exactly balance the temptation to shirk, with the barrier percentage approaching a fixed limit for large team sizes. As soon as the performance increase slows to anything less than quadratic, shirking eventually sets in and limits the possible size of the team. This implies that cooperation is sustainable in large organizational units, provided the problem‐solving processes used are powerful enough to ensure sufficient performance increases. Thus, effective problem‐solving methods are of double value, improving direct productivity and mitigating the social dilemma from team production. A manager should enlarge his or her organization up to the minimum of the limit set by the cooperation barrier and the exogenous performance limit.     

Economic crises in the thirties and today

In the context of the ongoing financial and economic crisis reference is frequently made to the Great Depression of the 1930s and fears are voiced that we may have embarked on a similar path. This article looks at the conditions prevailing back then and compares them with the present economic environment. From this some conclusions are drawn as to the likelihood of a recurrence of the disaster.     

Die Liberalisierung des Wohlfahrtsstaates und ihre Herausforderungen für das Pflegemanagement der Zukunft

Heilberufe - Die Liberalisierung des Wohlfahrtsstaates, ausgelöst durch den zunehmend globali sierten Wettbewerb, wird in der Zukunft auch wesentliche Auswirkungen auf die Anforderungen an die...