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21.
An important concern when planning research studies is to obtain maximum precision of an estimate of a treatment effect given a budget constraint. When research designs have a multilevel or hierarchical structure changes in sample size at different levels of the design will impact precision differently. Furthermore, there will typically be differential costs of enrolling additional units at different levels of the hierarchy. The optimal design problem in multilevel research studies involves determining the optimal sample size at each level of the design given specified design parameters and a specified marginal cost of recruitment at each level. The current work extends existing results by considering optimal design for (a) unbalanced random assignment designs and (b) regression discontinuity designs.  相似文献   
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This study is the first prospective longitudinal and clinical investigation of homesickness in children. The moods of 329 boys ages 8–16 were assessed on a daily basis during either a 2- or 4-week period of separation from primary caregivers. Results supported 4 hypotheses: (1) homesickness was prevalent and varied in intensity. 83% of the boys reported some homesickness on at least 1 day during their stay, and 5.8% experienced severe depression and anxiety; (2) homesickness was experienced as a combination of depression and anxiety, particularly the former; (3) younger boys were at greater risk for homesickness than older boys; and (4) homesickness presented most often as internalizing behavior and was sometimes detectable to observers who knew the boys. 63% of the boys who self-reported moderate or high levels of homesickness were judged by observers to be homesick. Inconsistent with popular notions, the most homesick boys became progressively more homesick over the course of their separation, experiencing a significant drop in homesickness just before reuniting with parents. The phenomenology of homesickness is discussed, as are issues of simultaneous depression and anxiety in children.  相似文献   
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RESEARCH FINDINGS: The purpose of this study was to examine the relations of children's effortful control and quality of relationships with teachers to school attitudes longitudinally in an ethnically diverse and economically disadvantaged sample. Data were collected as part of a larger intervention project during mid-fall, winter, and late spring (ns = 823, 722, and 758, respectively) for 2 cohorts of 3- to 5-year-olds (collected during 2 different school years). Children's effortful control was assessed in the fall with parents' and teachers' reports and 2 behavioral measures. Teacher-child relationship quality was assessed mid-year with teachers' reports of closeness and conflict. Attitudes toward school were assessed in late spring using teachers' and students' reports of school avoidance and liking. Effortful control, in general, was positively correlated with teacher-child closeness and school liking and negatively correlated with conflict and school avoidance. Using structural equation modeling and controlling for sex and ethnicity, we found that effortful control was positively related to teacher-child relationship quality, which in turn was positively related to school attitudes. Furthermore, the relation of effortful control to school attitudes was mediated by teacher-child relationship quality. PRACTICE OR POLICY: Results provide evidence for the importance of relational processes that take place within the classroom context and have implications for teachers and clinicians working to increase school success in ethnic minority and low-income children.  相似文献   
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The Resourced Open Learning Facility (ROLF) has been developed by the UK Skills Training Agency (STA) as a means of delivering off-the-job skill training in the national network of 60 skillcentres. STA introduced ROLF as a pilot scheme in six skillcentres at a time when the government was introducing a new programme for the long-term unemployed (Employment Training). The authors evaluated the pilot scheme and concluded that ROLF was working well for low achieving adults. ROLF is also important because it is a systematic approach to open learning delivery in a chain of centres under the same management. Most educational technology literature about open learning features materials, rather than delivery.  相似文献   
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Following the trend of consequential accountability in US public education, New York City introduced a teacher evaluation program during the 2013–2014 school year that linked teachers’ individual performance ratings with their students’ exam scores. As this program systemically alters the nature of teacher–student relationships by transforming students into the means to an end (teachers’ professional viability), this study investigated the implementation of this accountability program from the point of view of the teachers – those who were the subject of this new policy. This study of 15 teachers’ narratives from 3 distinct schools illuminates a social-organizational process that I refer to as mediated institutional assault – a perceived attack on the teachers’ sense of personhood and moral agency perpetrated by mediating figures whose actions were facilitated by bureaucratic policies and institutionally coordinated tools of control. Thus, this study reveals that the consequence of this new mode of accountability is not merely the threat of losing one’s job, but also an insidious form of psychological assault, which in its masked delivery violates teachers’ sense of relational morality and challenges deeply engrained beliefs about their role as educators.  相似文献   
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Four pigeons responded on a two-component multiple token-reinforcement schedule, in which tokens were produced according to a random-interval 30-sec schedule and exchanged according to a variable-ratio 4 schedule in both components. To assess the effects of contingent token loss, tokens were removed after every second response (i.e., fixed-ratio 2 loss) in one of the components. Response rates were selectively lower in the loss components relative to baseline (no-loss) conditions, as well as to the within-condition no-loss components. Response rates were decreased to a greater degree in the presence of tokens than in their absence. To control for the effects of changes in the density of token and food reinforcement, two parts consisted of additional conditions where food density and token loss were yoked to those in a previous loss condition. In the yoked-food condition, tokens were produced as usual in both components, but the overall density of food reinforcement in one of the components was yoked to that obtained during a previous token-loss condition. In the yoked token-loss condition, tokens were removed during one component of the multiple schedule at a rate that approximately matched the obtained rate of loss from a previous token-loss condition. Response rates in these yoked components were less affected than those in comparable loss components, despite similar densities of token, exchange, and food reinforcement. On the whole, the results support the conclusion that contingent token loss serves as an effective punisher with pigeons.  相似文献   
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