A Banzhaf share function for cooperative games in coalition structure

A cooperative game with transferable utility–or simply a TU-game– describes a situation in which players can obtain certain payoffs by cooperation. A value function for these games assigns to every TU-game a distribution of payoffs over the players. Well-known solutions for TU-games are the Shapley and the Banzhaf value. An alternative type of solution is the concept of share function, which assigns to every player in a TU-game its share in the worth of the grand coalition. In this paper we consider TU-games in which the players are organized into a coalition structure being a finite partition of the set of players. The Shapley value has been generalized by Owen to TU-games in coalition structure. We redefine this value function as a share function and show that this solution satisfies the multiplication property that the share of a player in some coalition is equal to the product of the Shapley share of the coalition in a game between the coalitions and the Shapley share of the player in a game between the players within the coalition. Analogously we introduce a Banzhaf coalition structure share function. Application of these share functions to simple majority games show some appealing properties.     

To test or not to test: do workplace drug testing programs discourage employee drug use?

Workplace drug testing programs are often met with intense criticism. Despite resistance among labor and consumer groups and a lack of rigorous empirical evidence regarding effectiveness, drug testing programs have remained popular with employers throughout the 1990s and into the current century. The present study analyzed nationally representative data on over 15,000 US households to determine whether various types of workplace drug testing programs influenced the probability of drug use by workers. The study estimated several empirical specifications using both univariate and bivariate probit techniques. The specification tests favored the bivariate probit model over the univariate probit model. Estimated marginal effects of drug testing on any drug use were negative, significant, and relatively large, indicating that drug testing programs are achieving one of the desired effects. The results were similar when any drug use was replaced with chronic drug use in the models. These results have important policy implications regarding the effectiveness and economic viability of workplace anti-drug programs.     

Disappointment without prior expectation: a unifying perspective on decision under risk

The central idea of Disappointment theory is that an individual forms an expectation about a risky alternative, and may experience disappointment if the outcome eventually obtained falls short of the expectation. We abandon the hypothesis of a well-defined prior expectation: disappointment feelings may arise from comparing the outcome received with anyof the gamble’s outcomes that the individual failed to get. This leads to a new, general form of Disappointment model. It encompasses Rank Dependent Utility with an explicit one-parameter probability transformation, and Risk-Value models with a generic risk measure including Variance, providing a unifying behavioral foundation for these models. JEL Classification D80 . D81     

The impossibility of the Paretian liberal and its relevance to welfare economics

The purpose of this study is to analyse the implications of Sen's impossibility result, the liberal paradox, for orthodox welfare economics. Because the rather special format of social choice theory makes it a little difficult to be sure of the relevance of this result, the whole dilemma is posed here in terms of a rather informal analysis of information al patterns.On the one hand, it is argued that the traditional approach to welfare economics, including both utilitarianism and Paretian ordinalism, contains severe informational constraints eliminating the use of all kinds of independent non-utility information in the social evaluation process. This property, called welfarism, is also present in the weak Pareto principle, which conflicts with even minimal requirements of personal liberty according to Sen's result.On the other hand, it is argued that there is in fact little to be resolved in this problem in spite of several attempts to circumvent the conflict. These studies are argued to be mainly ad hoc solutions to the formal problem and relevant only to the extent they indicate how severe restrictions are needed to avoid the paradox. The analogy with the prisoner's dilemma does not work either. Since liberal values are intrinsically non-welfaristic, the liberal paradox can be interpreted as only one, but a rather powerful, example of the informational deficiency of the orthodox approach.Finally, it is argued that the liberal paradox has striking implications for both the concept of preference and social optimum as well as empirical research on social welfare. This means that if the impossibility is to be taken seriously we need to revalue both the status of utility information and the role of the Pareto principle in social welfare analysis.The author is grateful to Professor Amartya Sen and Matti Tuomala for helpful comments and suggestions.     

On the emptiness of the stability set of order d

We know from Li's theorem (1993) that the stability set of order d may be empty for some preference profiles. However, one may wonder whether such situations are just rare oddities or not. In this paper, we partially answer this question by considering the restrictive case where the number of alternatives is the smallest compatible with an empty stability set. More precisely, we provide an upper bound on the probability for having an empty stability set of order d for the majority game under the Impartial Weak Ordering Culture assumption. This upper bound is already extremely low for small population and tends to zero as the number of individuals goes to infinity.     

The ratio bias phenomenon: fact or artifact?

The ratio bias—according to which individuals prefer to bet on probabilities expressed as a ratio of large numbers to normatively equivalent or superior probabilities expressed as a ratio of small numbers—has recently gained momentum, with researchers especially in health economics emphasizing the policy importance of the phenomenon. Although the bias has been replicated several times, some doubts remain about its economic significance. Our two experiments show that the bias disappears once order effects are excluded, and once salient and dominant incentives are provided. This holds true for both choice and valuation tasks. Also, adding context to the decision problem does not alter this finding. No ratio bias could be found in between-subject tests either, which leads us to the conclusion that the policy relevance of the phenomenon is doubtful at best.     

Knowledge representation by schemata in financial expert systems

This paper introduces the notion of knowledge structuring by schemata. A schema is a chunk of knowledge which generalizes the idea of functional dependence between pertinent concepts (objects). The rules are closely related to the schemata. Moreover the schemata are organized in a hierarchical network which takes into account the relative importance of the concepts. Examples are given in the financial field and the consequences with regards to knowledge engineering are discussed.     

Alexithymia and Gambling: A Risk Factor for All Gamblers?

The purpose of this study was to investigate alexithymia (in relation with depression) in three groups of French gamblers (n = 186) recruited in their gambling location: at the racetracks (n = 80 males; mean age 28.1 years), in the slot machine rooms (n = 65; 29 males, 36 females; mean age 34.6 years), and in the traditional gaming rooms (n = 41 males; mean age 36 years). Gambling behavior was measured by the South Oaks Gambling Screen and DSM-IV criteria for pathological gambling, Alexithymia by the Toronto Alexithymia Scale (TAS-20) and depression with the Beck Depression Inventory (BDI-13). For racetracks and slot machine gambling, pathological gamblers differed from non-pathological gamblers, regarding their alexithymia scores. These results remained stable after controlling for depression scores among the racetracks gamblers only. The relationship between alexithymia and depression depends on the type of pathological gambler. These findings are consistent with the idea of identifying clinically distinct subgroups of gamblers.     

Compact labelings for efficient first-order model-checking

We consider graph properties that can be checked from labels, i.e., bit sequences, of logarithmic length attached to vertices. We prove that there exists such a labeling for checking a first-order formula with free set variables in the graphs of every class that is nicely locally clique-width-decomposable. This notion generalizes that of a nicely locally tree-decomposable class. The graphs of such classes can be covered by graphs of bounded clique-width with limited overlaps. We also consider such labelings for bounded first-order formulas on graph classes of bounded expansion. Some of these results are extended to counting queries.     

Puerto rican drug users’ experiences of physical and sexual abuse: Comparisons based on sexual identities

This study integrates the results of quantitative and qualitative methods to elucidate the association between sexual identity and physical and sexual abuse among Puerto Rican drug users. A structured questionnaire was administered to 800 subjects in New York and 399 in Puerto Rico. A total of 93 subjects (7.9%) self‐identified as homosexual or bisexual. Gay males were significantly more likely than heterosexual males to report first occurrence of physical abuse by a family member in childhood. Both gay and bisexual males were more likely than their heterosexual counterparts to report first experiencing unwanted sex in childhood and intimate partner physical abuse later in life. Lesbians were more likely than female heterosexuals to report unwanted sex in childhood. Qualitative data were collected through in‐depth life histories with 21 subjects and suggest that gay and lesbian subjects perceive antihomosexual prejudice on the part of family members as one cause of childhood physical and sexual abuse.