A split-plot experiment in an automobile windshield fracture resistance test

The resistance of laminated glass to small projectile impact is examined with a design of experiments technique. The analysis follows a split-plot design, but other closely related approaches such as repeated measure analysis and multivariate analysis are also discussed and compared.     

Robust split‐plot designs

In many experimental situations, practitioners are confronted with costly, time consuming, or hard‐to‐change (HTC) factors. These practical or economic restrictions on randomization can be accommodated with a split‐plot design structure that minimizes the manipulation of the HTC factors. Selecting a good design is a challenging task and requires knowledge of the opportunities and restrictions imposed by the experimental apparatus and an evaluation of statistical performance among competing designs. Building on the well‐established evaluation criteria for the completely randomized context, we emphasize the unique qualitative and quantitative evaluation criteria for split‐plot designs. An example from hypersonic propulsion research is used to demonstrate the consideration of multiple design evaluation criteria. Published in 2007 by John Wiley & Sons, Ltd.     

Group contingencies, randomization of reinforcers, and criteria for reinforcement, self-monitoring, and peer feedback on reducing inappropriate classroom behavior.

Considerable research has demonstrated the effectiveness of interdependent and unknown dependent group contingencies on reducing inappropriate classroom behavior. Several investigators have focused on the addition of self-monitoring and peer feedback to these interdependent and unknown dependent group contingencies in order to further improve their effectiveness. In addition, another and separate line of research has examined group contingencies with the randomization of the reinforcement procedure as a means of improving the intervention effect. Absent in the present literature is a study that combines all of these various elements into one multicomponent intervention. Therefore, the present study focused on demonstrating the effectiveness of interdependent and unknown dependent group contingencies that also included self-monitoring, peer feedback, and the randomization of both reinforcers and criteria for reinforcement in reducing the frequency of inappropriate classroom behaviors. The results indicated large positive effects for this multicomponent intervention across all students. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Review of Randomization tests.

Reviews the book, Randomization Tests by Eugene S. Edgington (1980). Edgington begins his preface by suggesting that his book has two goals: "a practical guide for experimenters" and "a textbook for courses in applied statistics." As indicated above, the book is not the detailed and authoritative volume which experimenters need as a guide to randomization tests. However, Edgington's cogent criticisms of "the long-standing fiction of random sampling in experimental research" (p. iii) will lead experimenters to consider the merits of randomization tests. Similarly, the book is not thorough enough to be a successful textbook, but it should alert all teachers of statistics and experimental design to the importance of randomization and to the weakness of the random-sampling assumption in most statistical tests. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

响应-自适应随机化分组方法

目的: 介绍临床试验中一种随机化分组方法——响应-自适应随机化分组方法。方法: 结合模拟实验,介绍响应-自适应随机化分组方法中“胜者优先原则”和“随机化胜者优先原则”的思想和原理,并讨论响应-自适应随机化分组方法的优缺点及应用中需注意的问题。结果: 模拟结果显示,与传统的等比例分配结果相比,随机化胜者优先原则可以减少临床试验中的失败人数,而检验效能降低很少。结论: 与传统等比例分配相比,响应-自适应随机化分组方法更好地兼顾了伦理问题,值得临床界及统计学界重视,完善后可推荐在临床试验中应用。     

A statistical method for identifying different rules of interaction between individuals in moving animal groups

The emergent patterns of collective motion are thought to arise from application of individual-level rules that govern how individuals adjust their velocity as a function of the relative position and behaviours of their neighbours. Empirical studies have sought to determine such rules of interaction applied by ‘average’ individuals by aggregating data from multiple individuals across multiple trajectory sets. In reality, some individuals within a group may interact differently from others, and such individual differences can have an effect on overall group movement. However, comparisons of rules of interaction used by individuals in different contexts have been largely qualitative. Here we introduce a set of randomization methods designed to determine statistical differences in the rules of interaction between individuals. We apply these methods to a case study of leaders and followers in pairs of freely exploring eastern mosquitofish (Gambusia holbrooki). We find that each of the randomization methods is reliable in terms of: repeatability of p-values, consistency in identification of significant differences and similarity between distributions of randomization-based test statistics. We observe convergence of the distributions of randomization-based test statistics across repeat calculations, and resolution of any ambiguities regarding significant differences as the number of randomization iterations increases.     

基于半正定松弛与高斯随机化的电制燃料设施联合煤电机组优化经济调度方法

给出一种电制燃料设施与煤电机组联合运行的方案,可在产生电力、甲醇等重要二次能源的同时,提高发电系统灵活性。为了对联合机组进行合理调度,实现提升灵活性的同时确保经济性最优,提出了电制燃料设施联合煤电机组参与调频服务的优化经济调度方法。在充分考虑调频服务市场规则的情况下,构建了电制燃料设施与煤电机组联合参与单次调频的优化经济调度模型,相比已有研究该模型更加准确;针对含max函数的NP-hard非线性模型求解困难的问题,提出了采用分类转换并利用半正定松弛对原问题进行松弛,通过高斯随机化求解的方案。算例分析表明所提方法具有准确、高效的优势,为灵活能源设施与煤电机组联合运行的优化经济调度提供了参考。     

Accurate tests of statistical significance for rWG and average deviation interrater agreement indexes.

The authors demonstrated that the most common statistical significance test used with rWG-type interrater agreement indexes in applied psychology, based on the chi-square distribution, is flawed and inaccurate. The chi-square test is shown to be extremely conservative even for modest, standard significance levels (e.g., .05). The authors present an alternative statistical significance test, based on Monte Carlo procedures, that produces the equivalent of an approximate randomization test for the null hypothesis that the actual distribution of responding is rectangular and demonstrate its superiority to the chi-square test. Finally, the authors provide tables of critical values and offer downloadable software to implement the approximate randomization test for rWG type and for average deviation (AD)-type interrater agreement indexes. The implications of these results for studying a broad range of interrater agreement problems in applied psychology are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Enhancing the scientific credibility of single-case intervention research: Randomization to the rescue.

In recent years, single-case designs have increasingly been used to establish an empirical basis for evidence-based interventions and techniques in a variety of disciplines, including psychology and education. Although traditional single-case designs have typically not met the criteria for a randomized controlled trial relative to conventional multiple-participant experimental designs, there are procedures that can be adopted to create a randomized experiment in this class of experimental design. Our two major purposes in writing this article were (a) to review the various types of single-case design that have been and can be used in psychological and educational intervention research and (b) to incorporate randomized experimental schemes into these designs, thereby improving them so that investigators can draw more valid conclusions from their research. For each traditional single-case design type reviewed, we provide illustrations of how various forms of randomization can be introduced into the basic design structure. We conclude by recommending that traditional single-case intervention designs be transformed into more scientifically credible randomized single-case intervention designs whenever the research conditions under consideration permit. (PsycINFO Database Record (c) 2010 APA, all rights reserved)