A structured framework for assessing sensitivity to missing data assumptions in longitudinal clinical trials

The objective of this research was to demonstrate a framework for drawing inference from sensitivity analyses of incomplete longitudinal clinical trial data via a re‐analysis of data from a confirmatory clinical trial in depression. A likelihood‐based approach that assumed missing at random (MAR) was the primary analysis. Robustness to departure from MAR was assessed by comparing the primary result to those from a series of analyses that employed varying missing not at random (MNAR) assumptions (selection models, pattern mixture models and shared parameter models) and to MAR methods that used inclusive models. The key sensitivity analysis used multiple imputation assuming that after dropout the trajectory of drug‐treated patients was that of placebo treated patients with a similar outcome history (placebo multiple imputation). This result was used as the worst reasonable case to define the lower limit of plausible values for the treatment contrast. The endpoint contrast from the primary analysis was ? 2.79 (p = .013). In placebo multiple imputation, the result was ? 2.17. Results from the other sensitivity analyses ranged from ? 2.21 to ? 3.87 and were symmetrically distributed around the primary result. Hence, no clear evidence of bias from missing not at random data was found. In the worst reasonable case scenario, the treatment effect was 80% of the magnitude of the primary result. Therefore, it was concluded that a treatment effect existed. The structured sensitivity framework of using a worst reasonable case result based on a controlled imputation approach with transparent and debatable assumptions supplemented a series of plausible alternative models under varying assumptions was useful in this specific situation and holds promise as a generally useful framework. Copyright © 2012 John Wiley & Sons, Ltd.     

Robust inference from multiple test statistics via permutations: a better alternative to the single test statistic approach for randomized trials

Formal inference in randomized clinical trials is based on controlling the type I error rate associated with a single pre‐specified statistic. The deficiency of using just one method of analysis is that it depends on assumptions that may not be met. For robust inference, we propose pre‐specifying multiple test statistics and relying on the minimum p‐value for testing the null hypothesis of no treatment effect. The null hypothesis associated with the various test statistics is that the treatment groups are indistinguishable. The critical value for hypothesis testing comes from permutation distributions. Rejection of the null hypothesis when the smallest p‐value is less than the critical value controls the type I error rate at its designated value. Even if one of the candidate test statistics has low power, the adverse effect on the power of the minimum p‐value statistic is not much. Its use is illustrated with examples. We conclude that it is better to rely on the minimum p‐value rather than a single statistic particularly when that single statistic is the logrank test, because of the cost and complexity of many survival trials. Copyright © 2013 John Wiley & Sons, Ltd.     

基于SWOT模型的农村地区学前教育发展问题研究

SWOT分析法又称作态势分析法，能够将内部的优势劣势、外部的机会威胁逐条列举出来，并据此建立可视化矩阵图，系统全面地提出针对性策略。学前教育作为基础教育的短板，而农村地区学前教育又是学前教育中的短板。借助SWOT模型系统，全面地分析了农村地区学前教育发展的内部与外部的优势（S）、劣势（W）、机会（O）和威胁（T），进而提出相应的增长型战略、扭转型战略、多元化战略和防御型战略，以促进农村地区学前教育平稳、健康发展。     

Spatial approaches to social work – theoretical foundations and implications for practice and research

ABSTRACT

Spatial approaches have inspired and grounded the social sciences and social geography already for a longer time. Beyond these models, the theory discourse on social work developed innovative concepts and models of socio-spatial approaches. They set a special focus on aspects of individual and social development, the concept of acquirement and emancipatory approaches to spatial design. For interventions, special methods for socio-spatial analyses were developed. This article reflects the main approaches of this theory discourse and asks for its key implications for social work practice and research.     

The EPA Health Risk Assessment of Methylcyclopentadienyl Manganese Tricarbonyl (MMT)

This paper describes the U.S. Environmental Protection Agency's assessment of potential health risks associated with the possible widespread use of a manganese (Mn)-based fuel additive, methylcyclopentadienyl manganese tricarbonyl (MMT). This assessment was significant in several respects and may be instructive in identifying certain methodological issues of general relevance to risk assessment. A major feature of the inhalation health risk assessment was the derivation of Mn inhalation reference concentration (RfC) estimates using various statistical approaches, including benchmark dose and Bayesian analyses. The exposure assessment component used data from the Particle Total Exposure Assessment Methodology (PTEAM) study and other sources to estimate personal exposure levels of particulate Mn attributable to the permitted use of MMT in leaded gasoline in Riverside, CA, at the time of the PTEAM study; on this basis it was then possible to predict a distribution of possible future exposure levels associated with the use of MMT in all unleaded gasoline. Qualitative as well as quantitative aspects of the risk characterization are summarized, along with inherent uncertainties due to data limitations.     

民间公益服务组织路径选择的SWOT分析

伴随着市场经济体制改革,政府、市场、社会三位一体的系统正在构建。民间公益服务组织在社会中发挥着为政府分忧、为百姓解难的职责,SWOT框架清晰的分析了民间公益服务组织的处境,机遇与风险并存。抓住机遇、规避风险,社会资本理论为分析民间公益服务组织进而走向公民社会提供了新的视角,而这一切都需要建立在信任、互惠、合作三种路径模式的功效耦合基础之上。     

广西北部湾经济区石化产业发展的策略思考

面对国家政策的高度关注和大力支持以及经济发展的需要,广西北部湾经济区石化产业迎来了一个良好的发展契机.论文运用PEST和SWOT方法分析了广西北部湾经济区石化产业发展的基本情况,归纳了它的发展优势、劣势、机遇和威胁,并在此基础上提出了对其发展应采取的策略,可为相关部门提供决策参考.     

我国东西部发展差异的主成分分析

改革开放以来,我国那种大一统的传统经济模式被打破了.由于政策和区位的因素,各地采取了不同的发展模式,导致了各地发展速度和规模的差异.主成分分析法可以将多个变量综合成少数几个变量,以此来更好地揭示各种发展模式总体上的差异.     

佛山市总部经济发展的SWOT分析

总部经济是国内近年来出现的新的经济形态,发展总部经济成为当前国内城市之间新一轮竞争的热点。通过态势分析法(即SWOT分析法),对佛山市发展总部经济的优势、劣势以及面临的机遇和挑战进行分析,可以看出,佛山总部经济发展一方面具有明显的产业基础、行政体制、城市区位优势,另一方面又具有产业结构、人才资源等方面的劣势,可谓机遇和挑战并存。因此,制定契合佛山实际的发展战略对发展总部经济非常重要。     

哈尔滨鲜活农产品物流发展的SWOT分析

哈尔滨是黑龙江省鲜活农产品物流系统主要的配送中心。健全哈尔滨鲜活农产品物流体系是新农村建设的重点工作之一,也是当前农产品流通的重要环节。本文采用SWOT分析方法,分别阐述了哈尔滨鲜活农产品物流发展中的优势、劣势,外部环境中的机会、威胁,研究并选择适合哈尔滨鲜活农产品实际的发展战略。