Sharing the surplus and proportional values

Theory and Decision - We introduce a family of proportional surplus division values for TU-games. Each value first assigns to each player a compromise between her stand-alone worth and the average...     

Screening for disruptive behavior in adolescents at risk using the strengths and difficulties questionnaire

Disruptive behavior in adolescents is burdensome and may continue into adulthood if left unidentified. The strengths and difficulties questionnaire (SDQ) can screen for disruptive behavior, but its psychometric properties in high-risk samples and ability to predict delinquency warrant further investigation. In 1022 adolescents, we investigated the predictive validity (on average 1.9 years after screening) of the self-reported SDQ on disruptive behavior disorders and delinquency, measured with multi-informant questionnaires and structured interviews. We compared three scoring methods: total, subscale, and dysregulation profile scoring. In this high-risk sample, SDQ subscale scores predicted disruptive behavior outcomes best. Predictive values for the specific types of delinquency were small. Concluding, the SDQ can be used in high-risk settings for early identification of youth with disruptive behavior.     

Bayes Hilbert Spaces

A Bayes linear space is a linear space of equivalence classes of proportional σ‐finite measures, including probability measures. Measures are identified with their density functions. Addition is given by Bayes' rule and substraction by Radon–Nikodym derivatives. The present contribution shows the subspace of square‐log‐integrable densities to be a Hilbert space, which can include probability and infinite measures, measures on the whole real line or discrete measures. It extends the ideas from the Hilbert space of densities on a finite support towards Hilbert spaces on general measure spaces. It is also a generalisation of the Euclidean structure of the simplex, the sample space of random compositions. In this framework, basic notions of mathematical statistics get a simple algebraic interpretation. A key tool is the centred‐log‐ratio transformation, a generalization of that used in compositional data analysis, which maps the Hilbert space of measures into a subspace of square‐integrable functions. As a consequence of this structure, distances between densities, orthonormal bases, and Fourier series representing measures become available. As an application, Fourier series of normal distributions and distances between them are derived, and an example related to grain size distributions is presented. The geometry of the sample space of random compositions, known as Aitchison geometry of the simplex, is obtained as a particular case of the Hilbert space when the measures have discrete and finite support.     

Internal slackening scoring methods

We deal with the ranking problem of the nodes in a directed graph. The bilateral relationships specified by a directed graph may reflect the outcomes of a sport competition, the mutual reference structure between websites, or a group preference structure over alternatives. We introduce a class of scoring methods for directed graphs, indexed by a single nonnegative parameter α. This parameter reflects the internal slackening of a node within an underlying iterative process. The class of so-called internal slackening scoring methods, denoted by λ ^α , consists of the limits of these processes. It is seen that λ⁰ extends the invariant scoring method, while λ ^∞ extends the fair bets scoring method. Method λ¹ corresponds with the existing λ-scoring method of Borm et al. (Ann Oper Res 109(1):61–75, 2002) and can be seen as a compromise between λ⁰ and λ ^∞ . In particular, an explicit proportionality relation between λ ^α and λ¹ is derived. Moreover, the internal slackening scoring methods are applied to the setting of social choice situations where they give rise to a class of social choice correspondences that refine both the Top cycle correspondence and the Uncovered set correspondence.     

Body Satisfaction and Sexual Health in Dutch Female University Students

Studies in the field of body image have primarily addressed its negative aspects, such as body dissatisfaction. The present study focused instead on women who are satisfied with their bodies and on how body satisfaction relates to sexual health. A sample of 319 Dutch female university students completed an online survey that included items about body image evaluation, body image investment, overweight preoccupation, body image affect during sexual activity, sexual frequency, sexual functioning, and sexual self-esteem. We found that the level of body dissatisfaction was minimal in our sample. The majority reported neutral or mildly positive body evaluations, and in 30% of the sample these evaluations were clearly positive. Comparisons between women who reported positive versus neutral body evaluations showed that the body-satisfied women had lower body mass indexes (BMIs) and reported less body image investment, less overweight preoccupation, and less body self-consciousness during sexual activity. With regard to sexual health, they reported higher sexual self-esteem and better sexual functioning. Furthermore, we found that body image self-consciousness was negatively associated with sexual functioning, sexual self-esteem, and frequency of sexual activity with a partner. Body satisfaction did not account for a portion of the relationship of body self-consciousness during sexual activity with sexual health.     

Predicting ecstasy use among young people at risk: a prospective study of initially ecstasy-naive subjects

Our aim is to identify predictors of first-time ecstasy use in a prospective study among young people at risk. As part of the multidisciplinary Netherlands XTC Toxicity Study (NeXT), we monitored 188 subjects aged > or = 18 who were ecstasy-naive at baseline but seemed likely to start taking ecstasy in the near future. After an 11- to 26-month follow-up period, 160 respondents remained (85.1%; mean age 21.0 years, 58.1% females): 65 who took ecstasy at least once (ecstasy users) and 95 non-users. At baseline and four times during follow-up, respondents completed self-report questionnaires. Cox regression analysis was used to examine the effects of baseline respondent characteristics on incident ecstasy use. Development of peer group ecstasy use was analyzed by logistic regression. Intention to use ecstasy, low education, and current weekly cannabis use independently increased the hazard rate for first ecstasy use. Although ecstasy use among peers at baseline was not a predictor, the proportion of ecstasy users with ecstasy-using peers increased markedly during the study. Our results suggest that targeted prevention activities should focus in particular on young people who have strong intentions to take ecstasy, especially if they are also regular smokers of cannabis.     

Life-Satisfaction and Preference Drift

In this paper an empirical model is presented thataccounts for adaptation behavior in self-reports onlife-satisfaction. The model is used to determinepreference drift – adaptation to income levels – inlife-satisfaction. With preference drift, the effectof income on life satisfaction varies with the levelof life satisfaction. It is found that preferencedrift mainly occurs among individuals with a highlevel of life-satisfaction.