Mediation analyses abound in social and personality psychology. Current recommendations for assessing power and sample size in mediation models include using a Monte Carlo power analysis simulation and testing the indirect effect with a bootstrapped confidence interval. Unfortunately, these methods have rarely been adopted by researchers due to limited software options and the computational time needed. We propose a new method and convenient tools for determining sample size and power in mediation models. We demonstrate our new method through an easy-to-use application that implements the method. These developments will allow researchers to quickly and easily determine power and sample size for simple and complex mediation models.

Cyberbullying among school-aged children has received increased attention in recent literature. However, no empirical evidence currently exists on whether existing school-based antibullying programs are effective in targeting the unique aspects of cyberbullying. To address this important gap, the present study investigates the unique effects of the KiVa Antibullying Program on the frequency of cyberbullying and cybervictimization among elementary and middle school youth. Using data from a group randomized controlled trial, multilevel ordinal regression analyses were used to examine differences in the frequencies of cyberbullying and cybervictimization between intervention (N = 9,914) and control students (N = 8,498). The effects of age and gender on frequencies of cyber behaviors were also assessed across conditions. Results revealed a significant intervention effect on the frequency of cybervictimization; KiVa students reported lower frequencies of cybervictimization at posttest than students in a control condition. The effect of condition on the perpetration of cyberbullying was moderated by age. When student age was below the sample mean, KiVa students reported lower frequencies of cyberbullying than students in the control condition. We also found evidence of classroom level variation in cyberbullying and cybervictimization, suggesting cyberbullying is in part a classroom-level phenomenon. KiVa appears to be an efficacious program to address cyber forms of bullying and victimization. We discuss several unique aspects of KiVa that may account for the significant intervention effects. Results suggest that KiVa is an intervention option for schools concerned with reducing cyberbullying behavior and its deleterious effects on children's adjustment.

No abstract

This longitudinal study examines the mediating mechanisms by which the KiVa antibullying program, based on the Participant Role approach, reduces bullying and victimization among elementary school students. Both student-level mechanisms leading to reduced perpetration of bullying and classroom-level mechanisms leading to reductions in bullying and victimization are considered. Analyses are based on a sample of 7,491 students (49.5% boys) nested within 421 classrooms within 77 schools. At the beginning of program implementation, the children were in Grades 4, 5, and 6 (mean age 11.3 years). Multilevel structural equation modeling was used to analyze whether changes in the hypothesized mediators accounted for later reductions in the outcomes. At the student level, antibullying attitudes and perceptions regarding peers' defending behaviors and teacher attitudes toward bullying mediated the effects of KiVa on self-reported bullying perpetration. The effects on peer-reported bullying were only mediated by antibullying attitudes. At the classroom level, the program effects on both self- and peer-reported bullying were mediated by students' collective perceptions of teacher attitudes toward bullying. Also, perceived reinforcing behaviors predicted bullying but did not emerge as a significant mediator. Finally, bullying mediated the effects of the classroom-level factors on victimization. These findings enhance knowledge of the psychosocial developmental processes contributing to bullying and victimization and shed light on the key mechanisms by which school bullying can successfully be counteracted.

The present study investigated the effects of the KiVa antibullying program on students' anxiety, depression, and perception of peers in Grades 4-6. Furthermore, it was investigated whether reductions in peer-reported victimization predicted changes in these outcome variables. The study participants included 7,741 students from 78 schools who were randomly assigned to either intervention or control condition, and the program effects were tested with structural equation modeling. A cross-lagged panel model suggested that the KiVa program is effective for reducing students' internalizing problems and improving their peer-group perceptions. Finally, changes in anxiety, depression, and positive peer perceptions were found to be predicted by reductions in victimization. Implications of the findings and future directions for research are discussed.

Promoting self-determination has become best practice in special education. There remains, however, a paucity of causal evidence for interventions to promote self-determination. We conducted a group-randomized, modified equivalent control group design study of the efficacy of the Self-Determined Learning Model of Instruction to promote self-determination. Data on self-determination using multiple measures was collected with 312 high school students with cognitive disabilities in both a control and treatment group. We examined the relationship between the SDLMI and self-determination using structural equation modeling. After determining strong measurement invariance for each latent construct, we found significant differences in latent means across measurement occasions and differential effects attributable to the SDLMI. This was true across disability category, though there was variance across disability populations.

The purpose of this study was to uncover the day-to-day emotional profiles and dose-response relations, both within-persons and between-persons, associated with initiating one of two meditation practices, either mindfulness meditation or loving-kindness meditation. Data were pooled across two studies of midlife adults (N = 339) who were randomized to learn either mindfulness meditation or loving-kindness meditation in a six-week workshop. The duration and frequency of meditation practice was measured daily for nine weeks, commencing with the first workshop session. Likewise, positive and negative emotions were also measured daily, using the modified Differential Emotions Scale (Fredrickson, 2013). Analysis of daily emotion reports over the targeted nine-week period showed significant gains in positive emotions and no change in negative emotions, regardless of meditation type. Multilevel models also revealed significant dose-response relations between duration of meditation practice and positive emotions, both within-persons and between-persons. Moreover, the within-person dose-response relation was stronger for loving-kindness meditation than for mindfulness meditation. Similar dose-response relations were observed for the frequency of meditation practice. In the context of prior research on the mental and physical health benefits produced by subtle increases in day-to-day experiences of positive emotions, the present research points to evidence-based practices – both mindfulness meditation and loving-kindness meditation – that can improve emotional wellbeing.

Several types of alternative medicine have some potential for future clinical research. However, due to methodological inconsistencies across studies and the small body of evidence, no firm conclusions can be made at this time. Regarding alternative treatments, acupuncture and several types of meditative practice show the most promise for future scientific investigation. Likewise, magnesium, l-carnitine, and S-adenosylmethionine are nonpharmacological supplements with the most potential for further research. Individualized treatment plans that involve several pharmacological agents and natural remedies appear promising as well.