Marginal homogeneity,symmetry, and independence

A contingency table of the mc form provides a convenient summary of data when c individuals in a matched set9 each belonging to a different one of c classifications, are identified as belonging to one of m categories, A study in which matched sets (c=3) of 1 case, 1 hospital control, and 1 neighborhood control are classified into one of m=4 occupational categories would be an example, Independence in the cxm tables for each of the matched sets implies symmetry in the summary mc table with consequent marginal homogeneity. Adaptation of the Mantel-Haenszel procedure for testing independence to the case of many cxm tables so as to yield a chi square with (cl)(ml) degrees of freedom (DF) provides a test of marginal homogeneity in the summary mc table. This can be viewed as a test of symmetry directed against alternatives which would make for marginal inhomogeneity and can differ     

Power analysis for clustered non-continuous responses in multicenter trials

Power analysis for multi-center randomized control trials is quite difficult to perform for non-continuous responses when site differences are modeled by random effects using the generalized linear mixed-effects model (GLMM). First, it is not possible to construct power functions analytically, because of the extreme complexity of the sampling distribution of parameter estimates. Second, Monte Carlo (MC) simulation, a popular option for estimating power for complex models, does not work within the current context because of a lack of methods and software packages that would provide reliable estimates for fitting such GLMMs. For example, even statistical packages from software giants like SAS do not provide reliable estimates at the time of writing. Another major limitation of MC simulation is the lengthy running time, especially for complex models such as GLMM, especially when estimating power for multiple scenarios of interest. We present a new approach to address such limitations. The proposed approach defines a marginal model to approximate the GLMM and estimates power without relying on MC simulation. The approach is illustrated with both real and simulated data, with the simulation study demonstrating good performance of the method.     

Learning from a lot: Empirical Bayes for high‐dimensional model‐based prediction

Empirical Bayes is a versatile approach to “learn from a lot” in two ways: first, from a large number of variables and, second, from a potentially large amount of prior information, for example, stored in public repositories. We review applications of a variety of empirical Bayes methods to several well‐known model‐based prediction methods, including penalized regression, linear discriminant analysis, and Bayesian models with sparse or dense priors. We discuss “formal” empirical Bayes methods that maximize the marginal likelihood but also more informal approaches based on other data summaries. We contrast empirical Bayes to cross‐validation and full Bayes and discuss hybrid approaches. To study the relation between the quality of an empirical Bayes estimator and p, the number of variables, we consider a simple empirical Bayes estimator in a linear model setting. We argue that empirical Bayes is particularly useful when the prior contains multiple parameters, which model a priori information on variables termed “co‐data”. In particular, we present two novel examples that allow for co‐data: first, a Bayesian spike‐and‐slab setting that facilitates inclusion of multiple co‐data sources and types and, second, a hybrid empirical Bayes–full Bayes ridge regression approach for estimation of the posterior predictive interval.     

企业职工持股计划有效性的经济分析

以能否调动职工的工作积极性为标准,从个人效用最大化和企业效益最大化的角度,通过建立数学模型,探讨了职工持股计划的有效性,认为职工持股计划与企业员工的偏好,职工持股比例,工作交率及绩效工资的激励程度有关.     

浅析我国农业保险的路径依赖

文章以边际理论与博弈论为分析工具 ,分析了我国农业保险商品需求不足、供给有限的成因 ,探讨了政府、保险公司与农民三者之间的博弈及其均衡 ,指出实现政府、保险公司和农民三赢的策略是 :国家制定法律促使政府启动政策性农业保险 ,启动资金通过发行国债筹集 ;农业保险实行商业化运作 ,政府仅提供政策支持 ,对农民进行直接保费补贴 ,对保险公司进行税收减免 ;通过利益诱导机制 ,将农民推向保险公司 ,将保险公司引向农业。     

从边缘化人物看女性的失语——小说《井》的女性主义解读

小说<井>是澳大利亚当代著名小说家伊丽莎白·乔利的一部重要著作,反映了边缘化人物的生活和思想状态.本文从女性主义角度出发,从三个方面对小说进行解读:女性与父权的对立和屈从,女性与男性的对立和反叛,女性与自我的认同与分裂.小说的社会意义在于揭露了男权中心文化体系对女性的压制和迫害,表达了女性追求平等和自我的强烈愿望.     

多丽丝·莱辛小说中边缘人的社会写真

作为一名坚持文学社会功能的作家,莱辛的文学创作一直直面现实,关注被主流社会所遗忘的边缘人物。莱辛代表性作品中不同的边缘人书写有：非洲殖民地黑人﹑白人的生存困境;问题孩子对家人﹑社会关爱的渴求;及老年人生理﹑精神关爱的双重缺失。莱辛对不同层面边缘人的社会写真彰显了她的文学道德和责任感。     

日本对华直接投资的产业转移特征及趋势分析

通过分析20世纪日本对华直接投资的产业分布特征及新世纪的产业转移趋势,研究从政策上对日本对华直接投资加以正确的引导,以优化我国产业结构,提高我国的国际竞争力。     

Joint GEEs for multivariate correlated data with incomplete binary outcomes

This study considers a fully-parametric but uncongenial multiple imputation (MI) inference to jointly analyze incomplete binary response variables observed in a correlated data settings. Multiple imputation model is specified as a fully-parametric model based on a multivariate extension of mixed-effects models. Dichotomized imputed datasets are then analyzed using joint GEE models where covariates are associated with the marginal mean of responses with response-specific regression coefficients and a Kronecker product is accommodated for cluster-specific correlation structure for a given response variable and correlation structure between multiple response variables. The validity of the proposed MI-based JGEE (MI-JGEE) approach is assessed through a Monte Carlo simulation study under different scenarios. The simulation results, which are evaluated in terms of bias, mean-squared error, and coverage rate, show that MI-JGEE has promising inferential properties even when the underlying multiple imputation is misspecified. Finally, Adolescent Alcohol Prevention Trial data are used for illustration.     

捆绑策略对于低性能产品引入的价值

如何将低性能产品(低吸引力产品)引入现有高性能产品进行销售已成为企业关注的重要问题,尤其是当低性能产品具有各种边际成本结构以及顾客表现为在更长时间域理性选择购买时机的行为时.研究了捆绑策略对于低性能产品引入的价值,考虑了不引入低性能产品(只销售高性能产品)的基准策略以及引入低性能产品(同时销售两种产品)的完全捆绑策略、分开销售策略与混合捆绑策略.结论显示:当低性能产品的边际成本较低以及与高性能产品之间的竞食性较强时,不引入低性能产品对企业更有利.当低性能产品具有中等(较低)边际成本且与高性能产品之间的竞食性较弱时,企业应当采用混合捆绑策略引入低性能产品.此外,还分析了完全捆绑策略与分开销售策略的适用范围.