Publikationen

Field evidence suggests that agents belonging to the same group tend to behave similarly, i.e., behavior exhibits social interaction effects. Testing for such effects raises severe identification problems. We conduct an experiment that avoids these problems. The main design feature is that each subject simultaneously is a member of two randomly assigned and economically identical groups where only members (‘neighbors’) are different. In both groups subjects make contribution decisions to a public good. We speak of social interactions if the same subject at the same time makes group-specific contributions that depend on their respective neighbors’ contribution. Our results are unambiguous evidence for social interactions. A majority of subjects is very strongly influenced by the contributions of their respective neighbors. Roughly ten percent exhibit no social interactions.

In order to analyse whether women and men differ in their decision making under risk and uncertainty, we use data from the game show 'Who Wants to be a Millionaire?'. It turns out that i) there are gender differences in choosing a lottery or a certain value only for largestakes lotteries, ii) the decision making process differs significantly between small and large stake lotteries for both women and men, and iii) people with lower income tend to react more reluctant to choose a kind of certain value in order of a lottery. The results hold even after controlling for socio-economic variables.

Economic theory advances various arguments in favor of and against privatizing education. In this paper we investigate the extent to which these arguments influence voters opinions. We analyze two popular referenda in which some 400,000 voters in two Swiss cantons expressed their opinions on the issue of education vouchers and direct subsidies to private schools. We find that successful attempts to move towards a more privatized education system rest mainly on pure income effects, some other socio-economic determinants, ideological convictions, and possibly the perceived quality of the public schools. Peer-group and tax-burden effects, which play a prominent role in the theoretical literature, do not appear to significantly influence voting behavior.

This paper considers estimation of the regression function and its derivatives in nonparametric regression with fractional time series errors. We focus on investigating the properties of a kernel dependent function V (delta) in the asymptotic variance and finding closed form formula of it, where delta is the long-memory parameter. - General solution of V (delta) for polynomial kernels is given together with a few examples. It is also found, e.g. that the Uniform kernel is no longer the minimum variance one by strongly antipersistent errors and that, for a fourth order kernel, V (delta) at some delta > 0 is clearly smaller than R(K). The results are used to develop a general data-driven algorithm. Data examples illustrate the practical relevance of the approach and the performance of the algorithm.

Although there has been much attention in recent years on the effects of additive background risks, the same is not true for its multiplicative counterpart. We consider random wealth of the multiplicative form xy, where x and y are statistically independent random variables. We assume that x is endogenous to the economic agent, but that y is an exogenous and nontradable background risk, which represents a type of market incompleteness. Our main focus is on how the presence of the multiplicative background risk y affects risk-taking behavior for decisions on the choice of x. We characterize conditions on preferences that lead to more cautious behavior

The O-Ring theory provides a framework to analyse the emergence of firms organized as partnerships. The owner-managers of such entrepreneurial firms can benefit from ability matching within their production teams. However, they must also bear the project risk. Risk-aversion then induces a second-best solution. At the same time, integrated firms managed on behalf of risk-neutral residual-claimants face information and/or enforcement problems. Hence, they cannot organize ability-matched teams. It is shown that there exists an equilibrium such that groups of individuals sharing a superior ability level will found entrepreneurial firms. Low-quality individuals will be employed by managed firms which hire randomly.
The paper constitutes a significantly revised version of the study formerly entitled The Emergence of a New Economy: An O-Ring Approach , Department of Economics, University of Konstanz, Discussion Paper Series I 314.

While there is a broad literature on the general wage effect of training, little is known about the effects of different training forms and about the effects for heterogeneous training participants. This study therefore adds two aspects to the literature on earnings effects of training. First, the earnings effect of training is calculated for different types of employees, i.e. discriminating between qualification level, experience, job tenure, and other attributes. Second, we distinguish between the earnings impact of external and internal training. For our analysis, we use the Qualification and Career survey , a rich German data set with information on 0.1 percent of all individuals employed in Germany in 1998/1999. We use a one-step fullinformation maximum likelihood and a two stage least squares estimation to regress the impact of training participation on earnings correcting for the endogeneity of training participation. By using a broad list of employee and employer characteristics, we try to avoid omitted variable bias. We find the training earnings markup to be positively correlated with qualification and experience. The analysis of internal and external training reveals that this result is driven by external training only. Internal training does not have a significant earnings effect. The correction for selection into training leads to an increase in the training coefficients and a decrease of its significance.

In der Makroökonomik werden Liquiditätsfallen ohne Mikrofundierung als existent angenommen und die Japan-Krise hat Liquiditätsfallen zum aktuellen Diskussionsthema gemacht. Deshalb wird die Frage der Existenz von Liquiditätsfallen hier portfolio-theoretisch untersucht im Rahmen einer klassischen Mean-Variance-Ansatzes für zwei Assets (Geld und Wertpapiere). Vorausgesetzt wird eine stochastisch inflationäre Anlageumgebung ohne Geldillusion im Anlegerverhalten. Das Resultat ist negativ insofern als Liquiditätsfallen ausgeschlossen werden können, solange die erwartete Ertragsdifferenz der beiden Assets positiv zugunsten des Wertpapiers ausfällt (positiver nomineller Zinssatz auf Wertpapiere). Liquiditätsfallen sind ebenfalls ausgeschlossen, solange das Risiko der Ertragssatzdifferenz eine negative Rolle spielt, d.h. solange das Risiko größer null ist und solange gleichzeitig Risiko-Aversion besteht. Damit eine Liquiditätsfalle existiert muss entweder das Risiko überhaupt fehlen (Standardabweichung von null der Ertragsdifferenz) oder es darf keine Risikoaversion der Anleger geben.
Die in makroökonomischen Lehrbüchern als Liquiditätsfalle bezeichnete Konstellation (flacher Verlauf der Geldnachfragefunktion und positiver nomineller Zinssatz größer null) impliziert aus portfolio-theoretischer Sicht keine Liquiditätsfalle, sondern eine Wertpapierfalle.