When planning a study, sample size determination is one of the most important tasks facing the researcher. The size will depend on the purpose of the study, the cost limitations, and the nature of the data. By specifying the standard deviation ratio and/or the sample size ratio, the present study considers the problem of heterogeneous variances and non‐normality for Yuen's two‐group test and develops sample size formulas to minimize the total cost or maximize the power of the test. For a given power, the sample size allocation ratio can be manipulated so that the proposed formulas can minimize the total cost, the total sample size, or the sum of total sample size and total cost. On the other hand, for a given total cost, the optimum sample size allocation ratio can maximize the statistical power of the test. After the sample size is determined, the present simulation applies Yuen's test to the sample generated, and then the procedure is validated in terms of Type I errors and power. Simulation results show that the proposed formulas can control Type I errors and achieve the desired power under the various conditions specified. Finally, the implications for determining sample sizes in experimental studies and future research are discussed. 相似文献
Limited research has been conducted on dispositional mindfulness, posttraumatic stress disorder (PTSD) symptoms and academic burnout in Chinese adolescents following a tornado. The present study investigated the ways in which dispositional mindfulness is related to PTSD symptoms and academic burnout in Chinese adolescents following a tornado by considering the role of regulatory emotional self-efficacy. A total of 431 Chinese adolescents (mean age: 14.75 years) who had experienced a severe tornado 9 months prior to this study were recruited for this study. The results indicated that our model fit the data well [χ2/df = 2.774, CFI = 0.952, TLI = 0.934, RMSEA (90% CI) = 0.064 (0.051–0.077)], and revealed that regulatory emotional self-efficacy partially mediates the relationships between dispositional mindfulness and PTSD symptoms and academic burnout, respectively. The clinical implications and limitations of our research, and recommendations for future research, are discussed in this paper. 相似文献
Bi-ethnic adolescents of marriage migrant mothers in Korea are often encouraged to be “pure” Koreans for their adjustments and not given the opportunities to explore their ethnic identity or to learn about their mother’s culture of origin. Existing studies conducted with mono-ethnic minorities in other countries, however, do not support this belief. We tested a conceptual model on the role of ethnic socialization, ethnic identity and self-esteem on school adjustment among bi-ethnic adolescents in Korea based on social identity theory and theoretical models of ethnic socialization and ethnic identity. We used data from 2015 National Survey of Multicultural Families. The study sample consisted of 296 adolescents aged 9–18 who were born between Korean fathers and Vietnamese marriage migrant mothers. We used structural equation modeling to specifically examine the association between ethnic socialization in terms of parents’ linguistic socialization and adolescents’ school adjustment mediated by ethnic identity in the form of ethnic regard and self-esteem among bi-ethnic adolescents. The results verified the hypothesized model, showing positive relationships between linguistic socialization and ethnic regard, ethnic regard and self-esteem, self-esteem and school adjustment, and ethnic regard and school adjustment. Additionally, the results of bootstrapping test showed that the indirect effect of linguistic socialization on self-esteem through ethnic regard was significant. The indirect effect of ethnic regard on school adjustment through self-esteem was significant and the indirect effect of linguistic socialization on school adjustment via ethnic regard and self-esteem was also significant. These results shed light on the important role of ethnic identity fostered at home among bi-ethnic adolescents of marriage migrant mothers in Korea. 相似文献
Parent–adolescent relationships play an important role in protecting adolescents from depressive symptoms. However, there are no consistent conclusions about the extent to which fathers and mothers uniquely contribute to adolescents’ depressive symptoms. The present study aimed to acquire knowledge in this research area in two ways. First, this study separated the potential impacts of father–child and mother–child relationships on depressive symptoms in Chinese adolescents. Second, this study used a longitudinal design with nationally representative samples from the China Education Panel Survey. A total of 8794 middle school students in grade 7 completed measures of father–adolescent and mother–adolescent relationships, and depressive symptoms twice (T1 and T2; one-year interval). Results indicated that both positive father–adolescent and mother–adolescent relationships had negative effects on depressive symptoms in female adolescents. However, positive father-adolescent, not mother-adolescent, relationships had a negative effect on depressive symptoms in male adolescents. These findings suggest that positive parent–adolescent relationships could reduce early adolescents’ depressive symptoms, but positive father–adolescent and mother–adolescent relationships might have different protective effects on early adolescents’ depressive symptoms among male and female adolescents in China.
We investigated age-related differences in finger coordination during rotational hand actions. Two hypotheses based on earlier studies were tested: higher safety margins and lower synergy indices were expected in the elderly. Young and elderly subjects held a handle instrumented with five six-component force sensors and performed discrete accurate pronation and supination movements. The weight of the system was counterbalanced with another load. Indices of synergies stabilizing salient performance variables, such as total normal force, total tangential force, moments produced by these forces, and total moment of force were computed at two levels of a hypothetical control hierarchy, at the virtual finger-thumb level and at the individual finger level. At each level, synergy indices reflected the normalized difference between the sum of the variances of elemental variables and variance of their combined output, both computed at comparable phases over repetitive trials. The elderly group performed the task slower and showed lower safety margins for the thumb during the rotation phase. Overall, the synergy indices were not lower in the elderly group. In several cases, these indices were significantly higher in the elderly than in the younger participants. Hence, both main hypotheses have been falsified. We interpret the unexpectedly low safety margins in the elderly as resulting from several factors such as increased force variability, impaired feed-forward control, and the fact that there was no danger of dropping the object. Our results suggest that in some natural tasks, such as the one used in this study, healthy elderly persons show no impairment, as compared to younger persons, in their ability to organize digits into synergies stabilizing salient performance variables. 相似文献
Sex Roles - We introduce a new inventory measuring sex-based harassment intentions and threat perceptions grounded in gender status threat theories (Berdahl, 2007; Stephan et al., 2016). In Study 1... 相似文献