A novel equivalence probability weighted power prior for using historical control data in an adaptive clinical trial design: A comparison to standard methods

A standard two-arm randomised controlled trial usually compares an intervention to a control treatment with equal numbers of patients randomised to each treatment arm and only data from within the current trial are used to assess the treatment effect. Historical data are used when designing new trials and have recently been considered for use in the analysis when the required number of patients under a standard trial design cannot be achieved. Incorporating historical control data could lead to more efficient trials, reducing the number of controls required in the current study when the historical and current control data agree. However, when the data are inconsistent, there is potential for biased treatment effect estimates, inflated type I error and reduced power. We introduce two novel approaches for binary data which discount historical data based on the agreement with the current trial controls, an equivalence approach and an approach based on tail area probabilities. An adaptive design is used where the allocation ratio is adapted at the interim analysis, randomising fewer patients to control when there is agreement. The historical data are down-weighted in the analysis using the power prior approach with a fixed power. We compare operating characteristics of the proposed design to historical data methods in the literature: the modified power prior; commensurate prior; and robust mixture prior. The equivalence probability weight approach is intuitive and the operating characteristics can be calculated exactly. Furthermore, the equivalence bounds can be chosen to control the maximum possible inflation in type I error.     

Assessing efficacy in important subgroups in confirmatory trials: An example using Bayesian dynamic borrowing

Assessment of efficacy in important subgroups – such as those defined by sex, age, race and region – in confirmatory trials is typically performed using separate analysis of the specific subgroup. This ignores relevant information from the complementary subgroup. Bayesian dynamic borrowing uses an informative prior based on analysis of the complementary subgroup and a weak prior distribution centred on a mean of zero to construct a robust mixture prior. This combination of priors allows for dynamic borrowing of prior information; the analysis learns how much of the complementary subgroup prior information to borrow based on the consistency between the subgroup of interest and the complementary subgroup. A tipping point analysis can be carried out to identify how much prior weight needs to be placed on the complementary subgroup component of the robust mixture prior to establish efficacy in the subgroup of interest. An attractive feature of the tipping point analysis is that it enables the evidence from the source subgroup, the evidence from the target subgroup, and the combined evidence to be displayed alongside each other. This method is illustrated with an example trial in severe asthma where efficacy in the adolescent subgroup was assessed using a mixture prior combining an informative prior from the adult data in the same trial with a non-informative prior.     

试论藏语借词及其文化背景

藏语中的借词作为一种语言文化现象,从表面来看,在异族文化交流中起到了传递文化信息的作用;从深层来看,它始终反映着不同时代藏族与其他民族间的文化交流,从宏观上记录了各个层次文化交流的具体内容。加强藏语借词的研究,对于藏语言科学及文化考证等具有重要的学术价值。     

西部地区农户资金借贷行为影响因素研究——对西部地区49个自然村调查结果的实证分析

利用2008年对西部落后地区49个村庄资金借贷现状调查的数据,对影响农户资金借贷行为的因素进行大样本考察,以期为西部经济落后地区金融体系的改良和发展提供依据和新思路。从农户资金借贷发生率、融资偏好、借贷资金用途、借贷成本等方面考察了农户的资金借贷特征。在对农户资金借贷影响因素的研究上,首先提出影响农户资金借贷行为的理论假说,再选取多元逻辑斯蒂模型作为分析工具对其进行检验。统计结果表明农户的个人因素、家庭因素、偿债能力以及对信用社的主观感受对农户的资金借贷行为有着不同程度的影响。最后针对实际情况对西部地区农村金融体系的构建提出了政策建议。     

外来语探源--中、英、日语言与文化对比

外来语的产生不仅是单纯的语言现象,也是一种社会和文化现象.英语和日语中的外来语占其各自语言总词汇半数以上,而汉语中的外来语所占比例却很小,这一差别应归于中华民族,英吉利民族及大和民族各自不同的社会文化背景和语言文字特点.本文试图对中,英,日语言文化中的外来语形成的途径作一下比较探讨,以加深对外来语的认识.     

对我国"西方马克思主义"研究的一些认识

20多年来,我国对西方马克思主义研究争论的热点主要集中在对"西方马克思主义"概念的理解、这股思潮的性质、评价标准、以及对其中几个代表人物的评价上;目前的研究中还存在着若干尚未解决的带有根本性的问题;通过深入研究,大胆参考或借鉴其某些合理的创建性思想和研究问题的方法,对我们是有益的.     

假借造字法探究

针对古代汉语文字教学中的疑点 ,该文认为许慎所论“本无其字 ,依声托事”的假借为造字之法而非用字之法。从教学实践出发 ,兼及主要学者学派的观点 ,该文将“假借”概念分为广义假借与狭义假借。词义引申而假借和本有其字的假借应看作广义假借 ;“本无其字 ,依声托事”的造字假借应看作狭义假借。它是古今字产生的基础之一 ,是表意字与形声字之间的桥梁 ,在汉字发展史中起过重要的作用     

存在融资条件下证券组合选择的一种模糊决策方法

应用模糊可能性理论研究了在实际投资决策中存在融资条件下的证券组合选择问题。用证券收益的可能性均值和方差分别作为投资收益和风险的测度,将选择证券组合的概率均值-方差模型简化为一个线性规划模型,使得存在融资条件下有效投资组合的算法问题得到解决。最后,给出了一个数值例子,说明了这种决策方法是便捷有效的。     

地方政府直接举债的宪政条件

地方政府直接举债需具备如下要件:一是各级政府事权法治化,它可以有效预防中央政府强制向地方政府下放事权而不提供相应财力;二是本级政府应有一定的税收立法自主权和规范的转移支付来源,它是地方政府独立承担财政责任的物质基础;三是地方政府应当具有独立公法人地位,它是地方政府直接举债的法律人格;四是要有宪法、法律明确授权,它是主权信用健康的法治保障。     

Financial Market Globalization,Symmetry‐Breaking,and Endogenous Inequality of Nations

This paper investigates the effects of financial market globalization on the inequality of nations. The world economy consists of inherently identical countries, which differ only in their levels of capital stock. Each country is represented by the standard overlapping generations model, modified only to incorporate credit market imperfection. An integration of financial markets affects the set of stable steady states, as it changes the balance between the equalizing force of the diminishing returns technology and the unequalizing force of the wealth‐dependent borrowing constraint. The model is tractable enough to allow for a complete characterization of the stable steady states. In the absence of the international financial market, the world economy has a unique steady state, which is symmetric and stable. In the presence of the international financial market, symmetry‐breaking occurs under some conditions. That is, the symmetric steady state loses its stability and stable asymmetric steady states come to exist. In the stable asymmetric steady states, the world economy is endogenously divided into the rich and poor countries; the borrowing constraints are binding in the poor but not in the rich; the world output is smaller, the rich are richer and the poor are poorer in any of the stable asymmetric steady states than in the (unstable) symmetric steady state.