New critical values for the generalized t and generalized rank-sum procedures

Student's t test as well as Wilcoxon's rank-sum test may be inefficient in situations where treatments bring about changes in both location and scale. In order to rectify this situation, O'Brien (1988, Journal of the American Statistical Association 83, 52-61) has proposed two new statistics, the generalized t and generalized rank-sum procedures, which may be much more powerful than their traditional counterparts in such situations. Recently, however, Blair and Morel (1991, Statistics in Medicine in press) have shown that referencing these new statistics to standard F tables as recommended by O'Brien results in inflations of Type I errors. This paper provides tables of critical values which do not produce such inflations. Use of these new critical values results in Type I error rates near nominal levels for the generalized t statistic and slightly conservative rates for the generalized rank-sum test. In addition to the critical values, some new power results are given for the generalized tests.     

Les raisons de l’action collective : retour sur la mobilisation improbable des salariés d’hypermarchés

For the first time on 1 February 2008, three French labor unions (Force Ouvrière, Confédération Française Démocratique du Travail and Confédération Générale du Travail) called for a nationwide strike in hypermarket chains. Although the unions did not prolong the action on February 2, the wage earners of Hypermag Grand Large in Marseille went on strike for 16 days, demanding a special bonus of € 250, the recruitment of employees forced to work part-time into full-time positions and an increase in the employer's share in meal tickets (from € 3,05 to € 5,00). To explain why this movement occurred at that time and place, these employees’ objective interests and available resources are examined. This pair of concepts (as used in Marxism and then in the thought of Pierre Bourdieu, on the one hand, and, on the other, in utilitarian versions) suggests that labor actions by wage earners holding insecure jobs and having limited resources are improbable. Redefining the concept of the “interest” for a collective action in terms of subjective criteria helps us understand how what used to be tolerable ceases to be so, thus shedding light on the material processes that lead to forming the opinion “It's not fair”.     

PARTIALLY EQUINEIGHBOURED DESIGNS

This paper presents further results on a class of designs called equineighboured designs, ED. These designs are intended for field and related experiments, especially whenever there is evidence that observations in the same block are correlated. An ED has the property that every unordered pair of treatments occurs as nearest neighbours equally frequently at each level. Ipinyomi (1986) has defined and shown that ED are balanced designs when neighbouring observations are correlated. He has also presented ED as a continuation of the development of optimal block designs. An ED would often require many times the number of experimental materials needed for the construction of an ordinary balanced incomplete block, BIB, design for the same number of treatments and block sizes. Thus for a relatively large number of treatments and block sizes the required minimum number of blocks may be excessively large for practical use of ED. In this paper we shall define and examine partially equineighboured designs with n concurrences, PED (n), as alternatives where ED are practically unachievable. Particular attention will be given to designs with smaller numbers of blocks and for which only as little balance as possible may be lost.     

企业生态与企业发展

企业与其生态环境之间存在着相互关系, 通过对企业生态以及由之而引起的企业发展的 讨论和对前后工业社会的企业生态、企业形态及企业管理差异的比较, 使企业管理者认识到不 同的企业发展及管理模式是植根在什么样的企业生态环境之下, 什么样的生态环境适合于什 么企业发展、管理模式、企业生存及其原因.     

公司债务重组的实物期权方法研究

在考虑了公司所得税的情形下研究公司的策略性违约和债务重组问题, 分析表明对于标 准的债务合同, 股东权益最大化的违约时间通常与公司价值最大化的违约时间不一致; 如果不 允许债务重组或债权妥协, 破产清算一般将导致公司价值损失. 但是, 如果允许策略性债务违 约或对绝对优先权原则偏离, 股东权益价值最大化的破产决策将达到与公司价值最大化一致 的结果; 对于较高杠杆或较低杠杆公司, 债务重组具有重要的经济意义, 它可以避免杠杆公司 无效地提早或延迟破产清算.     

基于021 半无限规划的新产品开发计划方法

开发新产品, 加速产品更新换代, 是企业持续经营和不断发展的重要手段. 近年来随着 C IM S 技术的不断发展, 生产管理集成化程度的提高, 只对产品作定性的分析已远远不能满足 企业发展的需要. 本文提出一种新产品开发计划的定量分析方法. 该方法将所有产品分为四种 具有不同收益曲线与参数的产品类型. 每种类型产品的曲线参数由其经济特性确定. 在产品量 化描述的基础上, 给出了一种利用021 半无限规划(021 S IP) 制订新产品开发计划的数学模型 方法.     

Comparative Analyses of Pretest-Posttest Research Designs

Two common methods of analyzing data from a two-group pretest-posttest research design are (a) two-sample t test on the difference score between pretest and posttest and (b) repeated-measures/split-plot analysis of variance. The repeated-measures/split-plot analysis subsumes the t test analysis, although the former requires more assumptions to be satisfied. A numerical example is given to illustrate some of the equivalences of the two methods of analysis. The investigator should choose the method of analysis based on the research objective(s).     

A Note on Stagewise Regression

Suppose one estimates the coefficient β₂ in E[Y] = β₀ + β₁ X ₁ + β₂ X ₂ by stagewise regression. That is, first the model E[Y] ≌ β₀ + β₁ X ₁ is fit using simple linear regression followed by a simple linear regression of the residuals from this model on X ₂ to yield the estimator β₂. The ratio of the squared t statistic for the estimate b ₂ from multiple regression to the squared t statistic for β₂ is greater than or equal to 1.0 and is shown to be a convenient function of correlation coefficients among Y, X ₁, and X ₂. Examination of stagewise regression can provide useful insights when introducing concepts of multiple regression.     

小民族,大课题——以赫哲族为例

人数特别少的“小民族”在现代化过程中面临“生存发展”和“保存文化”的两难 ,这种两难取决于大小民族之间的态度、价值观和相互关系以及大民族对于“发展”的理解。在适当调整人们思维框架和参照系的条件下 ,以社区意识和区域发展为基础 ,小民族有可能找到既实现社会经济发展 ,又保持文化传统的发展模式     

Exposure Assessment for Pesticide Intake from Multiple Food Products: A Bayesian Latent‐Variable Approach

Pesticide risk assessment for food products involves combining information from consumption and concentration data sets to estimate a distribution for the pesticide intake in a human population. Using this distribution one can obtain probabilities of individuals exceeding specified levels of pesticide intake. In this article, we present a probabilistic, Bayesian approach to modeling the daily consumptions of the pesticide Iprodione though multiple food products. Modeling data on food consumption and pesticide concentration poses a variety of problems, such as the large proportions of consumptions and concentrations that are recorded as zero, and correlation between the consumptions of different foods. We consider daily food consumption data from the Netherlands National Food Consumption Survey and concentration data collected by the Netherlands Ministry of Agriculture. We develop a multivariate latent‐Gaussian model for the consumption data that allows for correlated intakes between products. For the concentration data, we propose a univariate latent‐t model. We then combine predicted consumptions and concentrations from these models to obtain a distribution for individual daily Iprodione exposure. The latent‐variable models allow for both skewness and large numbers of zeros in the consumption and concentration data. The use of a probabilistic approach is intended to yield more robust estimates of high percentiles of the exposure distribution than an empirical approach. Bayesian inference is used to facilitate the treatment of data with a complex structure.