Science Policy Choices and the Estimation of Cancer Risk Associated with Exposure to TCDD

United States regulatory agencies use no-threshold models for estimating carcinogenic risks. Other countries use no-threshold models for carcinogens that are genotoxic and threshold models for carcinogens that are not genotoxic, such as 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD or "dioxin"). The U.S. Environmental Protection Agency has proposed a revision of the carcinogenic potency estimate for TCDD that is based on neither a threshold nor a no-threshold model; instead, it is a compromise between risk numbers generated by the two irreconcilably different models. This paper discusses the revision and its implications.     

The theory of constraints: a methodology apart?—a comparison with selected OR/MS methodologies

Mingers (J. Oper. Res. Soc. 54 (2003) 559; Int. Trans. Oper. Res. 7 (2000) 673; J. Mingers, A. Gill (Eds.), Multimethodology: Towards the Theory and Practice of Combining Management Science Methodologies, Wiley, Chichester, 1997), Mingers and Brocklesby (Omega—Int. J. Manage. Sci. 25(5) (1997) 489; Systemist 18(3) (1996) 101) and others have sought to develop classificatory frameworks that would be useful in understanding the nature and characteristics of Operational Research/Management Science (OR/MS) methodologies and the philosophical assumptions underpinning them. This paper extends their work to the domain of methods and methodologies known as the Theory of Constraints (TOC). In particular, the paper helps position TOC methods and tools in relation to traditional OR/MS methodologies, methods and tools, and provides a basis for continuing multi-methodological development across the two domains.The paper concludes that the tools, techniques and methods of TOC can be viewed as a methodological set of complementary hard and soft tools and methods that contribute to all phases of activity and across all three social, personal and material dimensions of the Mingers–Brocklesby framework, and share the ontological and epistemological characteristics and assumptions of extant OR/MS methodologies.     

Archival data in program evaluation and policy analysis

Evaluators have typically avoided using existing data sets, choosing instead to collect their own information to maintain control over both the content and quality of the data. As demands on action researchers increase without provision for additional resources, primary data collection may become a luxury and the use of archival data may increase. Though archival data has practical and methodological advantages, there are limitations associated with the utilization of such information. The general problems with secondary data sources include the accuracy, acceptability and accessibility of the information. Following a discussion of these general problems, an example from the Civilian Health and Medical Program of the Uniformed Services (CHAMPUS) reimbursement data set is presented to illustrate specific difficulties with using archival data for evaluation research. Strategies are then presented for minimizing these difficulties, including determining the feasibility of utilization of such data sources, methods for assessing their accuracy and factors to consider in the data acquisition process.     

The governance of free/open source software projects: monolithic, multidimensional, or configurational?

This paper presents the results of a qualitative review and synthesis of the literature on open source governance, addressing four key questions: (1) How has open source software (OSS) governance been defined? (2) Has the phenomenon of OSS governance been conceptualized as a monolithic or multidimensional phenomenon? (3) What purposes is OSS governance hypothesized to serve? and (4) What are the dimensions of OSS governance, and how are these dimensions related to each other? The results of the review suggest a framework for future comparative and case study research on OSS governance, and they provide a basis for comparison with research on the governance of other distributed, community-based forms of content and creation.     

对W-B乘子置信域约束构造方法的改进及模型

Wong和Beasley针对数据包络分析(DEA)给出的乘子约束方法(W-B方法)常常会导致相应的模型没有可行解问题。指出了该问题出现的根源在于W-B方法在使用权重重要性概念时存在着逻辑不一致,并提出了一种构造乘子置信域(AR)约束的改进方法及相应的DEA/AR模型。改进方法及模型具有能够克服W-B方法所常常出现的某些乘子置信约束之间相互矛盾问题等三方面优点。经实例应用,验证了所提出的改进方法及相应的DEA/AR模型是切实可行的。     

Measuring Market‐Manufacturing Congruence: Conceptual Reaffirmations and Mathematical Modifications

Narasimhan and Wang (2000) provide a valuable addition to the research base by identifying a limitation in two of the original equations in Bozarth and Berry (1997), which we resolve, and a possible research direction for the calibration of indifference profiles. However, they fall short in their interpretation of key conceptual and methodological issues, including the distinction between indifference and ideal profiles, the difference between individual profile dimensions and overall congruence, and firm versus industry‐level manufacturing strategy research. We use this opportunity to clear up these points of confusion, and to reaffirm the value of the methodology introduced in Bozarth and Berry (1997).     

Development and Measurement Validity of a Task-Technology Fit Instrument for User Evaluations of Information System

Although many researchers have raised concerns about the lack of theoretical underpinnings for the user evaluation construct and the lack of measurement validity for specific instruments measuring it, the construct is still widely used in IS research. This paper reports on the development and measurement validity of a diagnostic tool used in recently published research to evaluate an organization's overall information systems and services. A distinctive feature of this instrument is that it is conceptually based on the task-technology fit theory in which the correspondence between information systems functionality and task requirements leads to positive user evaluations, and positive performance impacts. Specifically, the instrument development was guided by a task model of managerial decision making using recorded organizational information. This model suggested the different information systems functionalities required by users for that task, which then serve as the basis for a “task-technology fit” (TTF) instrument. The instrument thus measures the degree to which an organization's information systems and services meet the information needs of its managers. An extensive test of the measurement validity of the instrument is conducted using a sample of 357 users in 10 companies. It is found to have excellent reliability and discriminant validity for 12 dimensions of TTF, and also exhibits strong predictive validity. Finally, the instrument is compared to two other well-known user evaluation instruments. Though no single instrument can meet all needs, the instrument presented here should be considered an attractive option for researchers and practitioners seeking to measure the effectiveness of organizational information systems.     

魔鬼的笔迹(二)--前殖民话语,人种/族类见解和跨文化认同在德国殖民过程中的作用

萨摩亚人———“高贵的野蛮人”在殖民接管的前夜,最有影响的关于萨摩亚人的人种观念即为“高贵的野蛮人”[24](P205232)他者时,人们常常启用高贵的野蛮人这一套话,但这一比喻与其他比喻的不同尚待仔细分析。③我们都熟悉这样的说法:在19世纪社会理论的框架内,法国和苏格兰的启蒙运动把当代的非欧洲人说成是与欧洲人不同步,不是生活在一个时代。①大部分社会进化学说似乎不承认与非西方人有真正的亲族关系,它们也不认为人类的早期发展阶段有什么美德。最有影响的高贵的野蛮人的说法却恰恰相反。在这里,非西方人成了欧洲人的一个早期版本。…     

On a problem with singularity in comparison of linear experiments

For consistency, the parameter space in the Gauss-Markov model with singular covariance matrix is usually restricted by observation vector. This restriction arises some difficulties in comparison of linear experiments. To avoid it we reduce the problem of comparison from singular to nonsingular case.     

An adaptive seamless phase II/III design for oncology trials with subpopulation selection using correlated survival endpoints

Although the statistical methods enabling efficient adaptive seamless designs are increasingly well established, it is important to continue to use the endpoints and specifications that best suit the therapy area and stage of development concerned when conducting such a trial. Approaches exist that allow adaptive designs to continue seamlessly either in a subpopulation of patients or in the whole population on the basis of data obtained from the first stage of a phase II/III design: our proposed design adds extra flexibility by also allowing the trial to continue in all patients but with both the subgroup and the full population as co-primary populations. Further, methodology is presented which controls the Type-I error rate at less than 2.5% when the phase II and III endpoints are different but correlated time-to-event endpoints. The operating characteristics of the design are described along with a discussion of the practical aspects in an oncology setting.