A Bivariate Generalization of Gamma Distribution

In this article, a bivariate generalisation of the gamma distribution is proposed by using an unsymmetrical bivariate characteristic function; an extension to the non central case also receives attention. The probability density functions of the product and ratio of the correlated components of this distribution are also derived. The benefits of introducing this generalized bivariate gamma distribution and the distributions of the product and the ratio of its components will be demonstrated by graphical representations of their density functions. An example of this generalized bivariate gamma distribution to rainfall data for two specific districts in the North West province is also given to illustrate the greater versatility of the new distribution.     

The duration of unemployment in Russia

This paper uses longitudinal survey data to assess factors affecting the duration of unemployment in Russia. We examine four types of marginalised labour force participants, according to ILO guidelines and survey responses, and we estimate duration models for each type. It turns out that the sets of characteristics with the strongest effects on the duration are remarkably similar across the different unemployment definitions and model specifications. Therefore, despite the formidable practical measurement problems, problematic groups of individuals can actually be identified. Received: 27 January 1999/Accepted: 27 January 2000     

Consistency and Change in Children's Tattling on their Siblings: Children's Perspectives on the Moral Rules and Procedures of Family Life

Children's tattling on their siblings was observed in 39 families when children were 2- and 4- and 4- and 6-years of age. Tattling was more frequent among older siblings, and increased across time, despite a corresponding decrease in sibling transgressions against one another and an increase in parents' negative reactions to tattling. Tattling was largely truthful, implicit in form, and more likely to concern transgressions of what parents also regarded as more important standards. Among 4- and 6-year-olds, tattling was related to children's negative behaviour to one another and equally likely when children faced ongoing conflict issues and when they merely wished to inform parents of sibling wrongdoing. Parents generally allowed their children to tattle on one another, rarely reprimanded tattlers, but responded to the information contained in the tattlers' reports. The parents' responses were related to the quality of their children's tattling, but the children's tattling was unrelated to the likelihood that parents would react either positively or negatively to it. Results are discussed in terms of the place of tattling within the family system, with emphasis on the children's understanding of the implications of their parents' involvement in their own disputes.     

Adaptive Strategies,Gender Ideology,and Work‐Family Balance Among Dutch Dual Earners

Using questionnaire data on 149 Dutch dual‐earner couples with young children participating in the European Famwork study, we examine how adaptive strategies and gender ideology relate to parents’ perceived success in balancing work and family. Path analysis indicates that some adaptive strategies may harm individuals’ work‐family balance, particularly when they are made in the domain where the time budget is limited. In the need to succeed in multiple roles, however, endorsement of traits traditionally linked with the opposite gender, that is masculine traits for women and feminine traits for men, seems beneficial. We speculate that two underlying mechanisms — social pressure and time constraints — jointly operate in determining perceived success in balancing work and family.     

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.     

Estimating the prevalence of sensitive behaviour and cheating with a dual design for direct questioning and randomized response

Randomized response is a misclassification design to estimate the prevalence of sensitive behaviour. Respondents who do not follow the instructions of the design are considered to be cheating. A mixture model is proposed to estimate the prevalence of sensitive behaviour and cheating in the case of a dual sampling scheme with direct questioning and randomized response. The mixing weight is the probability of cheating, where cheating is modelled separately for direct questioning and randomized response. For Bayesian inference, Markov chain Monte Carlo sampling is applied to sample parameter values from the posterior. The model makes it possible to analyse dual sample scheme data in a unified way and to assess cheating for direct questions as well as for randomized response questions. The research is illustrated with randomized response data concerning violations of regulations for social benefit.     

A Bayesian model for ranking hazardous road sites

Summary.  Road safety has recently become a major concern in most modern societies. The identification of sites that are more dangerous than others (black spots) can help in better scheduling road safety policies. This paper proposes a methodology for ranking sites according to their level of hazard. The model is innovative in at least two respects. Firstly, it makes use of all relevant information per accident location, including the total number of accidents and the number of fatalities, as well as the number of slight and serious injuries. Secondly, the model includes the use of a cost function to rank the sites with respect to their total expected cost to society. Bayesian estimation for the model via a Markov chain Monte Carlo approach is proposed. Accident data from 519 intersections in Leuven (Belgium) are used to illustrate the methodology proposed. Furthermore, different cost functions are used to show the effect of the proposed method on the use of different costs per type of injury.     

Navigating norms and structures: young mothers’ pathways to economic independence

Understanding the complex relationships between childcare, education and work is crucial to acknowledging how young mothers express agency in their pathways to economic independence. Instead of considering them as a policy target group at risk for multiple reasons, this research reverses the perspective by focusing on young mothers’ agency in school and paid employment. The study is set in the Netherlands, where economic independence has become a focal point of social policy and practice, especially for young people. It explores how young mothers navigate norms and structures of education and employment, drawing on 18 months of participant observation and 41 semi-structured interviews with young mothers. Notions of ‘everyday’ and ‘bounded’ agency are used in analysing structural limitations (e.g. irregular working hours in ‘women’s jobs’, a lack of maternity leave at school) and norms (e.g. completing higher education and finding a good job versus being primary caretakers, enjoying children and being role models). School and workplace structures reinforce contradictory discourses of motherhood and economic independence. Young mothers exhibit agency in considering their options around job security, work experience, wages, student loans and spending time with children. In doing so, they navigate structural and normative collisions of economic independence and mothering.     

Differential Developmental Profiles of Adolescents Using Sexually Explicit Internet Material

This study used a person-centered approach to examine whether different developmental trajectories of boys’ and girls’ use of sexually explicit Internet material (SEIM) exist, which factors predict these trajectories, and whether sexual behavior develops differently for adolescents in these trajectories. A combination of latent class growth analysis on SEIM use and latent growth curve analysis on sexual behavior was used on four-wave longitudinal data of 787 eighth through tenth grade Dutch adolescents. Among boys, four SEIM use trajectories were identified, which were labeled Nonuse/Infrequent Use, Strongly Increasing Use, Occasional Use, and Decreasing Use. Among girls, a large Stable Nonuse/Infrequent Use and smaller Strongly Increasing Use and Stable Occasional Use trajectories were distinguished. Higher initial levels and/or stronger increases in SEIM use were predicted by demographic, social contextual, personal, and media use characteristics, including a stronger sexual interest, a higher degree of perceived realism regarding sexualized Internet content, and more permissive sexual attitudes. Moreover, initial levels of and, to some extent, developmental changes in sexual behavior varied for boys and girls in the different SEIM use trajectories. Whereas some adolescents showed concurrent low levels, or parallel strong increases in SEIM use and sexual behavior, a subgroup of boys decreased their SEIM use while increasing their sexual behavior.