Epidemiology of Peer Victimization and its Impact on Health-Related Quality of Life in Adolescents: a Longitudinal Study

A number of studies have computed the minimally important difference (MID) for health-related quality of life instruments. To determine whether there is consistency in the magnitude of MID estimates from different instruments. We conducted a systematic review of the literature to identify studies that computed an MID and contained sufficient information to compute an effect size (ES). Thirty-eight studies fulfilled the criteria, resulting in 62 ESs. For all but 6 studies, the MID estimates were close to one half a SD (mean = 0.495, SD = 0.155). There was no consistent relationship with factors such as disease-specific or generic instrument or the number of response options. Negative changes were not associated with larger ESs. Population-based estimation procedures and brief follow-up were associated with smaller ESs, and acute conditions with larger ESs. An explanation for this consistency is that research in psychology has shown that the limit of people's ability to discriminate over a wide range of tasks is approximately 1 part in 7, which is very close to half a SD. In most circumstances, the threshold of discrimination for changes in health-related quality of life for chronic diseases appears to be approximately half a SD.

This meta-analytic review of 148 studies on child and adolescent direct and indirect aggression examined the magnitude of gender differences, intercorrelations between forms, and associations with maladjustment. Results confirmed prior findings of gender differences (favoring boys) in direct aggression and trivial gender differences in indirect aggression. Results also indicated a substantial intercorrelation (r = .76) between these forms. Despite this high intercorrelation, the 2 forms showed unique associations with maladjustment: Direct aggression is more strongly related to externalizing problems, poor peer relations, and low prosocial behavior, and indirect aggression is related to internalizing problems and higher prosocial behavior. Moderation of these effect sizes by method of assessment, age, gender, and several additional variables were systematically investigated.

Bullying involvement in any form can have lasting physical and emotional consequences for adolescents. For programs and policies to best safeguard youth, it is important to understand prevalence of bullying across cyber and traditional contexts. We conducted a thorough review of the literature and identified 80 studies that reported corresponding prevalence rates for cyber and traditional bullying and/or aggression in adolescents. Weighted mean effect sizes were calculated, and measurement features were entered as moderators to explain variation in prevalence rates and in traditional-cyber correlations within the sample of studies. Prevalence rates for cyber bullying were lower than for traditional bullying, and cyber and traditional bullying were highly correlated. A number of measurement features moderated variability in bullying prevalence; whereas a focus on traditional relational aggression increased correlations between cyber and traditional aggressions. In our meta-analytic review, traditional bullying was twice as common as cyber bullying. Cyber and traditional bullying were also highly correlated, suggesting that polyaggression involvement should be a primary target for interventions and policy. Results of moderation analyses highlight the need for greater consensus in measurement approaches for both cyber and traditional bullying. Copyright © 2014 Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.