Progressive stress accelerated life tests under finite mixture models

In this paper, progressive stress accelerated life tests are considered when the lifetime of a product under use condition follows a finite mixture of distributions. The experiment is performed when each of the components in the mixture follows a general class of distributions which includes, among others, the Weibull, compound Weibull, power function, Gompertz and compound Gompertz distributions. It is assumed that the scale parameter of each component satisfies the inverse power low, the progressive stress is directly proportional to time and the cumulative exposure model for the effect of changing stress holds. Based on type-I censoring, the maximum likelihood estimates (MLEs) of the parameters under consideration are obtained. A special attention is paid to a mixture of two Rayleigh components. Simulation results are carried out to study the precision of the MLEs and to obtain confidence intervals for the parameters involved.     

The Impact of Survey Methodology and Context on Central Tendency,Nonresponse and Associations of Subjective Indicators of Government Performance

A comparison is given of (ordinal) measures of trust in government institutions that were collected with the aim of facilitating comparisons between different modes and contexts of data collection. Statistical analyses reveal that the mode effect could amount upto a 10% change of item nonresponse and a 9% change of the level of trust, whereas the context effect could lead upto a 19% change of the bivariate associations of trust. The observed changes of both measures of central tendency and of associations affect conclusions of social scientific research in isolated studies, which implies that comparative studies are seriously hampered by bias related to mode and context, two sources of obscurity adding to the two other threats which are differences of sample source and differences of question phrasing.     

Bedeutungswandel der Internen Revision in der internationalen Literatur: Corporate Governance,Risikomanagement und Bilanzskandale

Ohne Zusammenfassung     

Bestimmung von Kapitalkosten in diversifizierten Unternehmungen: Verfahrensvergleiche und Anwendungsempfehlungen

Die Notwendigkeit zur wertorientierten Führung und Steuerung von Unternehmungen gewinnt durch die zunehmende Professionalisierung der Kapitalmarktteilnehmer, die Basel-II-Richtlinien für Banken sowie die Neuregelung zum Goodwill Impairment weiter an Dynamik. Innerhalb der Wertkonzepte nehmen Kapitalkosten als zentraler „value driver“ eine herausragende Bedeutung ein. Vor diesem Hintergrund werden die unterschiedlichen Verfahren zur Ermittlung von Kapitalkosten, darunter auch das erst kürzlich vorgestellte Market-derived Capital Pricing Model, diskutiert und mittels eines zu entwickelnden Kriterienrasters systematisch miteinander verglichen. Schlie?lich entwickelt der Beitrag aus den Erkenntnissen des Verfahrensvergleichs sowie einer Expertenbefragung praktische Anwendungsempfehlungen.     

An efficient nonparametric estimator for models with nonlinear dependence

We provide a convenient econometric framework for the analysis of nonlinear dependence in financial applications. We introduce models with constrained nonparametric dependence, which specify the conditional distribution or the copula in terms of a one-dimensional functional parameter. Our approach is intermediate between standard parametric specifications (which are in general too restrictive) and the fully unrestricted approach (which suffers from the curse of dimensionality). We introduce a nonparametric estimator defined by minimizing a chi-square distance between the constrained densities in the family and an unconstrained kernel estimator of the density. We derive the nonparametric efficiency bound for linear forms and show that the minimum chi-square estimator is nonparametrically efficient for linear forms.     

Characterizations of negative multinomial distributions based on conditional distributions

In this paper characterizations of negative multinomial distributions based on conditional distributions have been studied.     

Gestaltung der Abschlussprüferhaftung – Implikationen theoretischer Modelle

Business scandals such as Enron, WorldCom or Parmalat have sparked intense discussions on the quality of corporate governance as well as the trustworthiness of statutory auditors. It is therefore no surprise that regulators have issued a large number of new regulations concerning auditing. The civil liability of external auditors has not changed in Germany, but such changes have already been announced by the German government. An increase in the existing liability cap in cases of negligent misconduct and extended third-party liability are planned. As a consequence, the results of analytical research on this topic are highly relevant. This paper summarises and comments on prior analytical research, in particular its assumptions and results, and focuses on important elements for the design of a liability regime. To this end, the paper addresses the questions of joint–and-several vs. proportionate liability rules, negligent vs. strict liability regimes, the extent of third party liability, and limited vs. unlimited liability.     

The generalized Stackelberg equilibrium of the all-pay auction with complete information

We characterize the equilibrium of the all-pay auction with general convex cost of effort and sequential effort choices. We consider a set of n players who are arbitrarily partitioned into a group of players who choose their efforts ‘early’ and a group of players who choose ‘late’. Only the player with the lowest cost of effort has a positive payoff in any equilibrium. This payoff depends on his own timing vis-a-vis the timing of others. We also show that the choice of timing can be endogenized, in which case the strongest player typically chooses ‘late’, whereas all other players are indifferent with respect to their choice of timing. In the most prominent equilibrium the player with the lowest cost of effort wins the auction at zero aggregate cost. We thank Dan Kovenock and Luis C. Corchón for discussion and helpful comments. The usual caveat applies. Wolfgang Leininger likes to express his gratitude to Wissenschaftszentrum Berlin (WZB) for its generous hospitality and financial support.     

Pitfalls of Normal-Gamma Stochastic Frontier Models

Although conceptually pleasing, normal-gamma frontier models lead to difficult estimation problems. It is shown here that unless the sample size reaches several thousands of observations the shape parameter of the gamma density is hard to estimate, and that this carries over to estimates of the stochastic frontier, the individual inefficiencies, and the allocation of the overall variance to the stochastic frontier and to the inefficiencies.