An empirical investigation of the statistical properties of generalized single-case randomization tests

Adapting Edgington's [J. Psychol. 90 (1975) 57] randomly determined intervention start-point model, Levin and Wampold [Sch. Psychol. Quart. 14 (1999) 59] proposed a set of nonparametric randomization tests for analyzing the data from single-case designs. In the present study, the performance of Levin and Wampold's four basic tests (independent start-point general and comparative effectiveness, simultaneous start-point general and comparative effectiveness) was examined with respect to their Type I error rates and statistical power. Of Levin and Wampold's four tests, all except the independent start-point comparative effectiveness test maintained their empirical Type I error rates and had acceptable power at larger sample-size and effect-size combinations. The one-tailed comparative intervention effectiveness test for the independent start-point model was found to be too liberal, in that it did not maintain its Type I error rate. Although a two-tailed application of that test was found to be conservative at longer series lengths, it had acceptable power at larger sample-size and effect-size combinations. The results support the utility of a versatile new class of single-case designs that permit both within- and between-unit statistical assessments of intervention effectiveness.     

人类基因组计划在西方引发的人性观思考

人类基因组计划在西方世界引起了相当广泛深入的关于人性观的思考。分子生物学的研究成果正在重新塑造人们对人类进化史和人类本身的认识。基因工程、干细胞研究等前沿领域产生的问题促使人们转向西方的传统哲学去寻找思想资源。尽管遗传决定论的陈旧观点在大众文化中仍时有所见。新的基因组学研究已开始采纳一种更全面的、兼顾历史与社会文化因素的角度。     

The interplay between parental behaviors and adolescents' sports-related values in understanding adolescents' dropout of organized sports activities

Using short-term longitudinal data, the primary goal of the present study was to examine the interplay between adolescents’ sports-related intrapersonal (e.g., sports values) and interpersonal factors (e.g., perceived parental involvement) in relation to sports dropout. A secondary goal was to explore the direction of effects in the association between intra- and interpersonal factors. A total of 420 adolescents (39% girls, M_age = 14.06; SD_age = 0.33) responded to a set of survey questions over two consecutive years. Results from structural equation modeling suggested that parental involvement predicted adolescents’ dropout one year later, via sports values. Further, the results suggested that the direction of influence is mainly from parents to adolescents. Overall, the findings indicate that adolescents whose parents attend their practices and games perceive sports activities as fun, important and useful; as a result, adolescents are less likely to dropout. The findings offer an improved understanding of how parents’ behaviors may influence adolescents’ dropout of organized sports.     

Cognitive impairment and the 10-year survival probability of a normal 62-year-old population

The predictive value of cognitive impairment together with demographic and health factors on long-term survival was evaluated. The population sample comprised 389 subjects, all 62 years old. Cognitive performances were measured using verbal, visuomotor and memory tests. Cognitive impairment was determined by comparing performances with norms derived from healthy controls. Ten years after testing, the probability of survival was 89% for the cognitively preserved subjects, 80% for those with mild impairment, and 71% for those with moderate impairment (p = 0.009). Relative risk (RR) for shortened survival was 1.7 (95% CI 0.9-3.2) for the mildly, and 2.6 (95% CI 1.4-4.8) for the moderately impaired. Perceived health problems were, as expected, related to reduced survival (p < 0.001, RR 3.6, 95% CI 2.1-6.0), and there was an association between cognitive impairment and impaired perceived health (p = 0.040). Multivariate analyses with Cox's regression models showed that cognitive impairment, in particular, impaired episodic memory had an association with survival, in addition to the expected effects. Thus, memory impairment may reflect very early signs of underlying disease, and so the findings provide predictive validity for the cognitive methods used.     

Shared leadership development and team performance: A new look at the dynamics of shared leadership

The present study offers new theoretical insights into the dynamics of shared leadership. Integrating arguments from shared leadership and team development theory, we examine how shared leadership changes over the course of a project team's life cycle and how this pattern of change relates to team performance. Guided by shared leadership theory and project team literature, we also explore team‐level factors, which may alter the pattern of shared leadership development. In particular, we propose that in project teams shared leadership develops in a nonuniform way, approximating an inverted U‐shaped pattern, increasing early in the team's life cycle, peaking around the midpoint, and then decreasing in the later phase. In turn, this development pattern relates positively to team performance. We also extend theory by explaining how specific team characteristics influence the pattern of shared leadership development. Using a three‐study approach, we empirically examine the hypothesized relationships and conclude with a general discussion of the theoretical and practical implications of our findings.     

The Influence of Judgment Calls on Meta-Analytic Findings

Previous research has suggested that judgment calls (i.e., methodological choices made in the process of conducting a meta-analysis) have a strong influence on meta-analytic findings and question their robustness. However, prior research applies case study comparison or reanalysis of a few meta-analyses with a focus on a few selected judgment calls. These studies neglect the fact that different judgment calls are related to each other and simultaneously influence the outcomes of a meta-analysis, and that meta-analytic findings can vary due to non–judgment call differences between meta-analyses (e.g., variations of effects over time). The current study analyzes the influence of 13 judgment calls in 176 meta-analyses in marketing research by applying a multivariate, multilevel meta-meta-analysis. The analysis considers simultaneous influences from different judgment calls on meta-analytic effect sizes and controls for alternative explanations based on non–judgment call differences between meta-analyses. The findings suggest that judgment calls have only a minor influence on meta-analytic findings, whereas non–judgment call differences between meta-analyses are more likely to explain differences in meta-analytic findings. The findings support the robustness of meta-analytic results and conclusions.     

人类基因组计划中的计算机科学

叙述了人类基因组计划（HGP）实施过程中计算机科学向基因组学领域的不断渗透及面临的挑战。基因组数据库及网络系统的构建与完善为基因组信息的交流提供了基础,一系列计算机软件的开发和改进简化了HGP这一繁重的劳动。在HGP的推动下,世界各大信息技术公司也加盟到基因组研究中,使生物学中融入了更多的计算机专业技能,有利于引进新的思维模式,开拓新的研究方法。但目前在基因组信息的交流与分析方面,标准化和精确性仍显不足,信息的处理能力也受到计算机存储量和运算速度的制约,这些问题将随着计算机科学的不断发展而逐渐解决。     

Paul Wachtel was ahead of his time

We enthusiastically endorse Wachtel's prescience in sounding the alarm about his three concerns. We argue that although he detected these trends nearly 30 years ago, they were just beginning to take hold in 1980 and it is only recently that they have become the norms in our field. We describe several manifestations of these trends that could not have been anticipated.