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1.
Grün B Hornik K 《Journal of the Royal Statistical Society. Series C, Applied statistics》2012,61(2):201-218
The measurement of human immunodeficiency virus ribonucleic acid levels over time leads to censored longitudinal data. Suitable models for dynamic modelling of these levels need to take this data characteristic into account. If groups of patients with different developments of the levels over time are suspected the model class of finite mixtures of mixed effects models with censored data is required. We describe the model specification and derive the estimation with a suitable expectation-maximization algorithm. We propose a convenient implementation using closed form formulae for the expected mean and variance of the truncated multivariate distribution. Only efficient evaluation of the cumulative multivariate normal distribution function is required. Model selection as well as methods for inference are discussed. The application is demonstrated on the clinical trial ACTG 315 data. 相似文献
2.
This article measures the degree to which academic economists have engaged in unethical behavior and the degree to which academic economists believe the profession as a whole engages in unethical behavior. Three main types of unethical behavior are examined: (1) falsification of research; (2) expropriation of graduate student research or including an undeserving co-author on a research paper; and (3) exchange of grades for gifts, money, or sex. Using a unique data set gathered at the 1998 American Economic Association (AEA) meetings, we find that there is a significant amount of misconduct, particularly in the second category. 相似文献
3.
Health care report cards have been endorsed as a mechanism for efficiently comparing key quantifiable aspects of performance across a range of health systems or plans. There are challenges in determining what to measure; how to gather and analyze data; and how to report, interpret, and use findings. Mental health has received little attention, and a consumer perspective is typically not included. The proposed MHSIP mental health report card (MMHRC) addresses these concerns. General issues for report cards are discussed, and the MMHRC is described in terms of content, data sources and quality, and analysis and reporting. 相似文献
4.
The Alvey Report has resulted in a growing interest in the UK in ‘expert systems’. It is fairly generally accepted, at least in the UK, that such systems function in a particular type of way, i.e. they arrive at decisions through a process of rule based inference. It is suggested that it may be more fruitful to regard rule based inference as one approach to the construction of expert systems, and that proven techniques of operational research may well be more useful in constructing other types of expert system. Alternative applications of expert systems are derived on the basis of a broader definition of an expert system in terms of what it does rather than how it does it. A parallel is drawn between these applications and some typical concerns of business research. It is suggested that a useful aid in identifying promising business applications of expert systems is to set up four ‘dimensions’ along which different types of system differ. Examples are given of where other techniques might conceivably be useful in applications of expert systems. 相似文献
5.
Arianne MJ Elissen Arno JA Van Raak Emmy WCC Derckx Hubertus JM Vrijhoef 《International Journal of Social Welfare》2013,22(1):80-89
Elissen AMJ, Van Raak AJA, Derckx EWCC, Vrijhoef HJM. Improving homeless persons' utilisation of primary care: lessons to be learned from an outreach programme in The Netherlands Faced with rising homelessness, countries around the world are in need of innovative approaches to caring for those without shelter, who, more often than not, suffer from severe health problems. We conducted a case study of an innovative Dutch Primary Care for the Homeless (PCH) programme to gain insight into clients' demographic characteristics, health problems and service use, and to develop an explanation for its success in increasing the latter. Our analyses are based on a combination of quantitative and qualitative data. The results of the study suggest that the success of the PCH programme can be explained by the providers' pragmatism and will to adapt their mode of care provision to the behavioural patterns and needs of their homeless clients. 相似文献
6.
This paper discusses characteristics of standard conjugate priors and their induced posteriors in Bayesian inference for von Mises–Fisher distributions, using either the canonical natural exponential family or the more commonly employed polar coordinate parameterizations. We analyze when standard conjugate priors as well as posteriors are proper, and investigate the Jeffreys prior for the von Mises–Fisher family. Finally, we characterize the proper distributions in the standard conjugate family of the (matrix-valued) von Mises–Fisher distributions on Stiefel manifolds. 相似文献
7.
This paper describes the GRASP computer aided design system for modelling and evaluating industrial robot workplaces. GRASP satisfies a range of simulation needs within the context of designing, implementing and operating industrial robotic systems. The GRASP software may be used to investigate robots operating by themselves or, more likely, as part of an integrated cell. Facilities within GRASP assist workplace layout, position and velocity evaluations, clash detection and co-ordination between items. A robot library exists and is being extended, and an embryo off-line programming facility has been used under restricted conditions. GRASP has been used to help solve a wide range of practical industrial robot problems and has proved itself technically, and also as an educational tool, by showing how a proposed system would operate. The paper describes the facilities within GRASP. 相似文献
8.
语篇翻译中的英汉衔接手段对比——布什9.11演讲分析 总被引:1,自引:0,他引:1
衔接是为了实现语篇的连贯,是语篇重要的组成部分。英汉两种语言有着不同的衔接手段,文章通过布什9. 11演讲与其中译本的对比研究,揭示出衔接手段在英汉语篇中不同的运用和侧重,明确翻译时应根据语言各自的特点以及语篇体裁的要求,灵活变通或转换衔接手段,从而忠实再现原文。 相似文献
9.
本文对内蒙古西部重要寺院阿拉善南寺的创建者和六世达赖喇嘛 《仓央嘉措(tshangs dbyangs rgya mtsho)传》的作者阿旺多尔济(ngag dbang rdo rje)的生平事迹作了较为系统的叙述。作者从比较多的蒙、藏、汉文献中找出有关阿旺多尔济的零散记载,把它们按年代顺序整理汇编,从而比较完整地描述了 他一生中的重要活动。这对研究六世达赖喇嘛和《仓央嘉措传》一书及其作者,有 一定的参考价值。 相似文献
10.
Thomas Reutterer Kurt Hornik Nicolas March Kathrin Gruber 《Zeitschrift für Betriebswirtschaft》2017,87(3):337-358
This research presents a new approach to derive recommendations for segment-specific, targeted marketing campaigns on the product category level. The proposed methodological framework serves as a decision support tool for customer relationship managers or direct marketers to select attractive product categories for their target marketing efforts, such as segment-specific rewards in loyalty programs, cross-merchandising activities, targeted direct mailings, customized supplements in catalogues, or customized promotions. The proposed methodology requires customers’ multi-category purchase histories as input data and proceeds in a stepwise manner. It combines various data compression techniques and integrates an optimization approach which suggests candidate product categories for segment-specific targeted marketing such that cross-category spillover effects for non-promoted categories are maximized. To demonstrate the empirical performance of our proposed procedure, we examine the transactions from a real-world loyalty program of a major grocery retailer. A simple scenario-based analysis using promotion responsiveness reported in previous empirical studies and prior experience by domain experts suggests that targeted promotions might boost profitability between 15 % and 128 % relative to an undifferentiated standard campaign. 相似文献