With reference to social-ecological, self-determination, attributional, and social cognitive theories, the current study examined whether gender, age, altruistic motivation to defend victims, and tendency to blame the victims, at the individual level, and the prevalence of reinforcing and defending, at the classroom level, were associated with bullying. A sample of 901 Swedish students (9-13years old, M=11.00, SD=.83) from 43 classrooms filled out a questionnaire. Multilevel regression analyses revealed that the perpetration of bullying was positively associated with the prevalence of reinforcing at the classroom level and blaming the victims at the individual level, whereas it was negatively associated with altruistic motivation to defend victims of bullying at the individual level. Furthermore, students with high altruistic motivation to defend victims of bullying were less inclined to bully, independent of the classroom level of reinforcing. The current study suggests that bullying prevention and intervention programs should: explicitly target bystander behaviors, in particular to reduce the prevalence of reinforcing bullying; include efforts to strengthen altruistic self-concept and motivation to defend victims; and prevent, challenge, and counteract tendencies among students to blame the victim.

Using the social-ecological and social cognitive theories as integrated guiding frameworks, the present study examined whether moral disengagement and defender self-efficacy at the individual level, and moral disengagement, quality of teacher–student relationships and quality of student–student relationships at the classroom level were associated with passive bystanding and defending in bullying situations. Participants were 900 Swedish students from 43 classrooms, ranging in age from 9 to 13 years. Multilevel regression analyses revealed that passive reactions by bystanders were associated with greater moral disengagement and less defender self-efficacy. Defending, in turn, was associated with less moral disengagement and greater defender self-efficacy and classroom student–student relationship quality. Furthermore, students who scored high in moral disengagement were even less prone to defend victims when the classroom student–student relationship quality was low, but more prone to act as defenders when the classroom student–student relationship quality was high. In addition, the negative association between defender self-efficacy and passive bystanding was stronger both in classrooms with higher student–student relationship quality and in those with lower class moral disengagement. Implications for prevention are discussed.

The aim of the present study was to examine whether class climate and class moral disengagement each contribute to explain different levels of victimisation among classes. Eight-hundred-and-ninety-nine children from 43 Swedish elementary school classes participated in the current study. Class moral disengagement, class relational climate and peer victimisation were assessed by a self-report questionnaire. In order to account for the clustered nature of the data with students nested within school classes, a multilevel regression model was analysed. Consistent with our hypotheses, and after controlling for age, gender and ethnic background at the individual level and class size and the proportion of boys at the class level, both class relational climate and class moral disengagement uniquely contributed to explaining the between-class variance in victimisation. Thus, the findings suggested that victimisation is less likely to occur in classes characterised by a positive, warm, fair and supportive relational pattern between children and between teachers and children, and by lower levels of class moral disengagement.

Consistent negative correlations between sibship size and cognitive performance (as measured by intelligence quotient and other mental aptitude tests) have been observed in past empirical studies. However, parental decisions on family size may correlate with variables affecting child cognitive performance. The aim of this study is to demonstrate how selection bias in studies of sibship size effects can be adjusted for. We extend existing knowledge in two aspects: as factors affecting decisions to increase family size may vary across the number and composition of current family size, we propose a sequential probit model (as opposed to binary or ordered models) for the propensity to increase family size; to disentangle selection and causality we propose multilevel multiprocess modelling where a continuous model for performance is estimated jointly with a sequential probit model for family size decisions. This allows us to estimate and adjust for the correlation between unmeasured heterogeneity affecting both family size decisions and child cognitive performance. The issues are illustrated through analyses of scores on Peabody individual achievement tests among children of the US National Longitudinal Survey of Youth 1979. We find substantial between-family heterogeneity in the propensity to increase family size. Ignoring such selection led to overestimation of the negative effects of sibship size on cognitive performance for families with 1-3 children, when known sources of selection were accounted for. However, the multiprocess modelling proposed could efficiently identify and control for such bias due to adverse selection.

Some people will follow a different educational path despite having the intellectual ability to do well in school. This study explored how educational achievers and underachievers were different from each other in middle adulthood as well as examined which individual and contextual factors in adolescence were important to educational underachievement in middle adulthood. Participants are a school cohort followed from age 10 to middle adulthood (N = 1,326) and are from the Swedish longitudinal research program entitled Individual Development and Adaptation. This study focuses on a subgroup of Individual Development and Adaptation participants (n = 304) with above average intelligence (Mean IQ = 119.39, SD = 5.97). Study findings showed that a minority of adolescents in the study focal group (26%) did not complete high school, and women were more likely to educationally underachieve than men. A simultaneous multilevel logistic regression, with school class accounted for in the analysis, showed that for those of above average intelligence parents socioeconomic status and school grades were the strongest predictors of educational attainment. Finally, in midlife, underachievers had lower incomes and occupational levels, drank less frequently, and rated their health as worse than achievers. Study implications are discussed in terms of ways to advance the field of gifted underachievement and in relation to Swedish gifted educational policy.

This paper demonstrates how to plan a contingent valuation experiment to assess the value of ecologically produced clothes. First, an appropriate statistical model (the trinomial spike model) that describes the probability that a randomly selected individual will accept any positive bid, and if so, will accept the bid A, is defined. Secondly, an optimization criterion that is a function of the variances of the parameter estimators is chosen. However, the variances of the parameter estimators in this model depend on the true parameter values. Pilot study data are therefore used to obtain estimates of the parameter values and a locally optimal design is found. Because this design is only optimal given that the estimated parameter values are correct, a design that minimizes the maximum of the criterion function over a plausable parameter region (i.e. a minimax design) is then found.

This paper concerns design of contingent valuation experiments when interest is in knowing whether respondents have positive willingness to pay and, if so, if they are willing to pay a certain amount for a specified good. A trinomial spike model is used to model the response. Locally D- and c-optimal designs are derived and it is shown that any locally optimal design can be deduced from the locally optimal design for the case when one of the model parameters is standardized. It is demonstrated how information about the parameters, e.g., from pilot studies, can be used to construct minimax and maximin efficient designs, for which the best guaranteed value of the criterion function or the efficiency function is sought under the assumption that the parameter values are within certain regions. The proposed methodology is illustrated on an application where the value of the environmentally friendly production of clothes is evaluated.