Overconfidence in Currency Markets

This paper tests the influential hypothesis, typically attributed to Friedman (1953), that irrational traders will be driven out of financial markets by trading losses. The paper’s main finding is that overconfident currency dealers are not driven out of the market. Traders with extensive experience are neither more nor less overconfident than their inexperienced colleagues. We first provide evidence that currency dealers are indeed overconfident, which is notable since they get daily trading practice and face intense financial incentives to accuracy.Overconfidence, imperfect rationality, currency dealers, survival of imperfect rationality

Through Their Own Words: Towards a New Understanding of Leadership Through Metaphors

This paper suggests that metaphors are essential to understanding leadership. Metaphors can serve as underlying, organizing structures of leadership thinking and experience, and they can be mobilized in order to accomplish interpersonal goals. The literature on leadership abounds with metaphors, such as leadership as game, sport, art, or machine. The multitude of leadership metaphors used by authors and leaders alike appears determined by a complex interplay of personal, situational, and cultural factors. However, analysis of leadership interviews indicates that these metaphors center on experientially significant nuclei of meaning. By examining the entailments of leadership metaphors on such dimensions as highlighted and hidden leadership aspects, or the suggested relationship between leader and follower, metaphor analysis allows the exploration of leadership conceptualizations on an experiential level. An exploratory grid presents possible entailments of selected metaphors on important dimensions of leadership. We propose that the study of leadership metaphors can provide valuable lessons to leaders. For example, effective leadership may require a rich and situationally attuned metaphorical vocabulary. Leadership metaphors carry implicit suggestions about values—what is good, what should be done, and how—and may also allow for new insights into the ethics of leadership

Computing Bayes Nash Equilibrium Strategies in Auction Games via Simultaneous Online Dual Averaging

Auctions are modeled as Bayesian games with continuous type and action spaces. Computing equilibria in auction games is computationally hard in general and no exact solution theory is known. We introduce algorithms computing distributional strategies on a discretized version of the game via online convex optimization. One advantage of distributional strategies is that we do not have to make any assumptions on the shape of the bid function. Besides, the expected utility of agents is linear in the strategies. It follows that if our regularized optimization algorithms converge to a pure strategy, then they converge to an approximate equilibrium of the discretized game with high precision. Importantly, we show that the equilibrium of the discretized game approximates an equilibrium in the continuous game. In a wide variety of auction games, we provide empirical evidence that the method approximates the analytical (pure) Bayes Nash equilibrium closely. This speed and precision is remarkable, because in many finite games learning dynamics do not converge or are even chaotic. In standard models where agents are symmetric, we find equilibrium in seconds. The method allows for interdependent valuations and different types of utility functions and provides a foundation for broadly applicable equilibrium solvers that can push the boundaries of equilibrium analysis in auction markets and beyond

Buchbesprechung

Bucgbesprechung zu: (1) Rainer Bauböck, Eva Ersbøll, Kees Groenendijk, Harald Waldrauch (Hg.): Acquisition and Loss of Nationality: Policies and Trends in 15 European States, Volume 1, Comparative Analyses, IMISCOE Research. Amsterdam: Amsterdam University Press 2006, 499 S. (2) Rainer Bauböck, Eva Ersbøll, Kees Groenendijk, Harald Waldrauch (Hg.): Acquisition and Loss of Nationality: Policies and Trends in 15 European States, Volume 2, Country Analyses, IMISCOE Research. Amsterdam: Amsterdam University Press 2006, 588 S. (3) Rainer Bauböck, Bernhard Perchinig, Wiebke Sievers (Hg.): Citizenship Policies in the New Europe, IMISCOE Research. Amsterdam: Amsterdam University Press 2007, 314 S

Strukturelle Versäulungen in Österreich und den Niederlanden: Gemeinsamkeiten, Unterschiede, Auswirkungen

'Vorbei ist die Blütezeit des Lager- bzw. Säulendenkens in Österreich und den Niederlanden. Im Unterschied zum niederländischen Säulensystem, das vier Säulen aufwies (die protestantische, die katholische, die humanistisch-liberale und die sozialistische), kennzeichnete das österreichische Säulensystem zwei (die katholisch-konservative und die sozialistische) bzw. 'zweieinhalb' Säulen ('zweieinhalb', da das deutsch-nationale Lager in sich zu zersplittert war, um eine eigene Säule zu bilden). Der Vergleich struktureller Versäulungen in Österreich und den Niederlanden ist insofern von besonderem Interesse, als beide Staaten in der jüngeren Vergangenheit durch neokorporatistische bzw. konsoziative politische Systeme geprägt waren und zu Zielpunkten umfangreicher Einwanderungen geworden sind, sich jedoch in den Einwanderungspolitiken und politischen Diskursen über ImmigrantInnen deutlich unterscheiden: Im Unterschied zu den Niederlanden, welche man als eine pluralistische Demokratie versäulter Minderheiteninteressen im Sinne des Konsoziationalismus bezeichnen konnte, bildete die Konkordanzdemokratie Österreichs lange Zeit geradezu die Antithese zu einem pluralistischen Österreich.' (Autorenreferat)'The heydays of 'camps' or 'pillars' in Austria and The Netherlands are over: In contrast to the situation in the Netherlands, where four pillars used to exist (protestant, catholic, humanist-liberal and socialist), the Austrian pillar-system was defined by two (catholic-conservative, socialist) respectively by two and a half ('two and a half' because the national-German 'camp' was too weak for building its own pillar). Both democracies, the Austrian and the Dutch, have been shaped by what is called a neo-corporatist or consociational political system and both countries faced relatively large flows of immigration. Nevertheless, the political discourses concerning immigrants are significantly different in Austria and the Netherlands: In contrast to the Netherlands, which could be described as a pluralistic democracy of minority interests, formed as pillars (in the sense of consociationalism), the Austrian consensus democracy almost formed the antithesis for a pluralistic system in Austria.' (author's abstract

Species delineation and genetic variation of Hiatella "arctica" (Bivalvia, Heterodonta) in the Mediterranean Sea

Hiatella ist eine marine Gattung innerhalb der Klasse Bivalvia, die mit Ausnahme von tropischen Gewässern weltweit vorkommt. Die Lebensweise von Hiatella ist vielfältig: sie lebt in Felsspalten, epiphytisch oder epizoisch, oder auch im Gewebe von Schwämmen. Die Schalenform ist maßgeblich der ökologischen Nische angepasst und demzufolge hoch variabel. Es ist nach dem heutigen Wissensstand unklar, wie viele Arten von Hiatella im Mittelmeer vorkommen. Zu diesem Zweck wurde in dieser Diplomarbeit ein molekularer Ansatz gewählt. Es wurden vier Populationen im Mittelmeer anhand von molekularen Markern untersucht. Ein mitochondrialer Genbereich bestehend aus Teilen der COI, COIII, ATP6, 16SrRNA sowie zwei "non coding" Regionen, wurde sequenziert. Mit diesem Datensatz wurden eine Bayes’sche Analyse, eine Netzwerkanalyse sowie eine molekulare Varianzanalyse (AMOVA) durchgeführt. Die Analysen ergaben, dass alle Tiere conspezifisch sind. Weiters gibt es eine starke Korrelation zwischen genetischer Differenzierung und der geographischen Distanz. Diese molekularen Daten unterstützen die Hypothese, dass es sich im Mittelmeer um eine einzige, phänotypisch variable Art handelt, die in dieser Studie als Hiatella „arctica“ bezeichnet wird. Die Oberflächenströmungen im Mittelmeer scheinen das Verbreitungspotential von Hiatella „arctica“ demzufolge nicht negativ zu beeinflussen. Mögliche Erklärungen für die beträchtliche intraspezifische Variation liegen zum einen im hohen Verbreitungspotential der Larven, sowie der juvenilen und adulten Tieren. Andererseits kann durch die Fähigkeit, unterschiedliche Lebensräume zu besiedeln das Habitat als durchgehend betrachtet werden. Folglich scheint es im Mittelmeer mit Ausnahme der geographischen Distanz kaum physischen Barrieren zu geben, welche den Genfluss zwischen Populationen von Hiatella "arctica" einschränken.Hiatella is a common bivalve genus with a widespread marine distribution. It is not clear, however, how many species are represented in the Mediterranean Sea due to the high plasticity in shell form and the resulting problems in species delineation. Hence, in this study a molecular approach is used to distinguish between morphological and ecological similar species. Specimens were collected from different habitats and geographically distinct parts of the Mediterranean Sea. Two fragments of the mitochondrial genome, including parts of ribosomal (16S rRNA) and protein coding genes (COI, COIII, ATP6) as well as two non coding regions, were used for genealogcal analyses and analyses of molecular variance (AMOVA). The analyses show that all specimens belong to the same species, referred to as Hiatella "arctica". Furthermore, the genetic differentiation among populations is strongly correlated with the geographic distances. The capacity to colonise geographically distinct parts of the Mediterranean Sea probably results from The high dispersal ability of Hiatella "arctica" probably result from high dispersal abilities, from the ecological plasticity, from the continuous habitat, seacurrents and anthropogenic influence. There seem no physic barriers, with the exception of geographic distance, that limit gene flow beteen populations of Hiatella "arctica" in the Mediterranean Sea

On the Convergence of Learning Algorithms in Bayesian Auction Games

Equilibrium problems in Bayesian auction games can be described as systems of differential equations. Depending on the model assumptions, these equations might be such that we do not have a rigorous mathematical solution theory. The lack of analytical or numerical techniques with guaranteed convergence for the equilibrium problem has plagued the field and limited equilibrium analysis to rather simple auction models such as single-object auctions. Recent advances in equilibrium learning led to algorithms that find equilibrium under a wide variety of model assumptions. We analyze first- and second-price auctions where simple learning algorithms converge to an equilibrium. The equilibrium problem in auctions is equivalent to solving an infinite-dimensional variational inequality (VI). Monotonicity and the Minty condition are the central sufficient conditions for learning algorithms to converge to an equilibrium in such VIs. We show that neither monotonicity nor pseudo- or quasi-monotonicity holds for the respective VIs. The second-price auction's equilibrium is a Minty-type solution, but the first-price auction is not. However, the Bayes--Nash equilibrium is the unique solution to the VI within the class of uniformly increasing bid functions, which ensures that gradient-based algorithms attain the {equilibrium} in case of convergence, as also observed in numerical experiments

Einleitung: Religion.bildet. Divers, plural und säkular in der Wissensgesellschaft?

akzeptierte Manuskriptversio

Renormalisation and fixed points in Hilbert Space

The energies of low-lying bound states of a microscopic quantum many-body system of particles can be worked out in a reduced Hilbert space. We present here and test a specific non-perturbative truncation procedure. We also show that real exceptional points which may be present in the spectrum can be identified as fixed points of coupling constants in the truncation procedure.Comment: 4 pages, 1 tabl