Extensible Statistical Software: On a Voyage to Oberon

Abstract

Recent changes in software technology have opened new possibilities for statistical computing. Conditions for creating efficient and reliable extensible systems have been largely improved by programming languages and systems that provide dynamic loading and type-safety across module boundaries, even at run time. We introduce Voyager, an extensible data analysis system based on Oberon, which tries to exploit some of these possibilities.     

Technological Tools in the Introductory Statistics Classroom: Effects on Student Understanding of Inferential Statistics

While technology has become an integral part of introductory statistics courses, the programs typically employed are professional packages designed primarily for data analysis rather than for learning. Findings from several studies suggest that use of such software in the introductory statistics classroom may not be very effective in helping students to build intuitions about the fundamental statistical ideas of sampling distribution and inferential statistics. The paper describes an instructional experiment which explored the capabilities of Fathom, one of several recently-developed packages explicitly designed to enhance learning. Findings from the study indicate that use of Fathom led students to the construction of a fairly coherent mental model of sampling distributions and other key concepts related to statistical inference. The insights gained point to a number of critical ingredients that statistics educators should consider when choosing statistical software. They also provide suggestions about how to approach the particularly challenging topic of statistical inference. This revised version was published online in July 2006 with corrections to the Cover Date.     

Minitab在统计学专业实践课程中的案例拓展

在Minitab软件的数据整理、数据计算规则下,以Minitab宏为框架,设计了一类控制图优化在统计学专业实践环节中的应用案例.既拓展了统计学专业实践环节的内容,也是对Minitab控制图绘制模块的功能补充.研究展示了功能性统计软件在统计学专业实践教学中的应用前景.     

Rapid Prototyping of Optimization Algorithms Using COIN-OR: A Case Study Involving the Cutting-Stock Problem

The rate at which research ideas can be prototyped is significantly increased when re-useable software components are employed. A mission of the Computational Infrastructure for Operations Research (COIN-OR) initiative is to promote the development and use of re-useable open-source tools for operations research professionals. In this paper, we introduce the COIN-OR initiative and survey recent progress in integer programming that utilizes COIN-OR components. In particular, we present an implementation of an algorithm for finding integer-optimal solutions to a cutting-stock problem.     

Uncertainty Modelling in Software Development Projects (With Case Study)

A project scheduling model tailored specifically for software development projects is proposed in this study. The model incorporates uncertainties related to activity durations and network topology. The first type of uncertainty exists due to error-prone coding which might result in elongated task durations caused by validation and debugging sessions. Furthermore, in practice, macro-activities represent groups of sub-tasks in order to simplify the planning and monitoring of the project. Due to the aggregation, it is more difficult to be precise on the duration of a macro-activity.The uncertainty related to the network topology is due to common database design issues or program modules shared among parallel tasks in the project network. These tasks become associated with each other through uncertain Start-to-Start (SS) precedence relationships. On the other hand, SS lags may also be the outcome of technological precedence relationships among pairs of activities. However, the imprecision underlying the work content of a predecessor activity leads to uncertain SS lags.Software development projects are human-intensive projects and hence, the duration of a task depends on the skill of the person assigned to the job as well as his/her learning rate. Thus, a task may be realized by alternative staff members which results in different expected task durations. Hence, a realistic model proposed for software development projects should incorporate staff assignment features under the uncertainties discussed above. In this study, we develop a mathematical model for software development projects and propose heuristic solution methods to be used by the project co-ordinator in preparing the project plan. The heuristic algorithms developed here are tested on real data provided by a consulting firm undertaking software development projects from manufacturing companies in Turkey.     

Integrating Geographical Information Systems and Multi-Criteria Methods: A Case Study

This paper presents an application of the integration between Geographical Information Systems (GIS) and Multi-Criteria Decision Analysis (MCDA) to aid spatial decisions. We present a hypothetical case study to illustrate the GIS–MCDA integration: the selection of the best municipal district of Rio de Janeiro State, Brazil, in relation to the quality of urban life. The best municipal district is the one that presents the closest characteristics to those considered ideal by the decision-maker. The approach adopted is the Multi-Objective Linear Programming (MOLP) and the chosen method is the Pareto Race.     

空间众包环境下的任务定价模型研究

在综合考虑平台、商家和会员三方相互作用的基础上,通过建立包含任务动态分配机制的动态规划模型,结合金融定价思想刻画任务定价问题,并通过空间可视化对珠三角地区劳务众包平台数据进行实证研究.为提高模型的实用性,利用K-means聚类分析对任务打包并引入激励规则对动态定价模型进行了改进.最后,通过模拟仿真得出改进后模型的任务完成率为88.10%,相比平台现有定价模型(62.50%)和改进前的动态定价模型(85.20%)任务完成情况有较大幅度的提升.为基于地理位置的服务平台的商品定价、以及地理位置信息与平台会员的关系等实证和应用研究提供了理论与实践参考.     

Collaborative Teams in a University Statistics Course: A Case Study of How Differing Value Structures Inhibit Change

In a rapidly changing world, individuals need the intellectual agility, problem‐solving skills, and increased interdependence that are not developed in a traditional classroom. Despite years of reform efforts, little change in practice has been observed. This is a case study of the efforts of a statistics professor who used collaborative learning to prepare his students for the challenges of the 21^st century. The nature of the statistics course, the intentions of the professor, and the interactions and feedback of his students are analyzed in terms of their underlying value structures ( Beck & Cowan, 1996 ). Conflicting expectations and experiences, particularly with assessment, resulted in dissatisfaction and frustrations for the professor and the students.     

居民生活碳排放抽样调查方案设计:以青海省为例

调查方案设计是居民生活碳排放调查及数据分析的基础和保证.以大量文献和作者在居民生活碳排放调查中的实践经验为基础,立足调查方案的科学性和实践操作的可行性,以青海省为例,从居民生活碳排放调查的统计量选取、抽样框的构建、抽样方法的选择和样本量的确定、调查方案实施的详细步骤4方面综述性归纳了一套居民生活碳排放调查方案设计的方法,以期为居民生活碳排放研究提供参考.     

低碳电网扩张策略:以南方电网公司为例

研究了需求随机环境下电力企业关于电源建设与电力调度的最优决策;考虑电源机组的能源结构约束与运营发电期内的碳排放总量约束,构建了以总成本最小化为目标的带补偿二阶段随机规划模型;定性分析了模型的最优解与装机容量等其它参数之间的联系;以南方电网公司为例,基于真实的数据并考虑政府的规划建议与企业自身的低碳化发展要求,利用情景生成法求解随机规划模型。结果反映了电力系统发展过程中环保绩效与总成本之间的矛盾之外,为企业在实践运作中计划期的电力建设决策以及运营期的发电决策提供了一些有价值的建议。     

Probabilistic Analysis of Failures in Power Transmission Networks and Phase Transitions: Study Case of a High-Voltage Power Transmission Network

We present the failure analysis of a study case of a high-voltage power transmission network using the mathematical model of cascading blackouts introduced in Carreras et al. (Chaos 12:985–994, 2002). When the load of the network is randomly perturbed, we study the probability density function of the measure of the size of the resulting blackout as a function of the mean load level. The mathematical model used approximates the network with an undirected graph made of generator, load and junction nodes connected by branches representing the lines of the network. The electric flow in the network is found solving the optimal DC power-flow problem and the sequence of events causing a cascading blackout is simulated using a numerical scheme. The analysis points out the existence of values of the mean total power demand such that for higher values when the blackout size measure increases the decay of the blackout size measure probability density function changes from being best fitted by a negative exponential to being best fitted by an inverse power law. The analogies between this phenomenon and the phase transition phenomenon studied in statistical mechanics are discussed. The website: contains some auxiliary material including animations that helps the understanding of this paper. The numerical experience reported in this paper has been obtained using the computing grid of ENEA (Roma, Italy).     

Reconstructing the Adjusted Census for Florida: A Case Study in Data Examination

Abstract

This article is a case study in the value of close examination of available data when one is attempting to make inferences. The article is also an example of what can be done to reconstruct government files when data have been concealed, whether for administrative or political reasons, as here, or to preserve confidentiality. The various methods currently used are under review by a panel under the aegis of the Committee on National Statistics of the National Research Council. The upshot of our work is that even suppressing half of the microlevel data in a file need not daunt a determined and reasonably adroit reconstructor equipped with modern computers. The particular problem discussed here arose due to a bizarre set of political and legal circumstances, explained in Section 1, whereby the U.S. Department of Commerce released a tape consisting of the adjusted population (cross-classified by age, race, and gender) of half the Census Blocks in the nation, together with certain summary adjusted information. This article concerns techniques used to fill in the other half of the adjusted block data for possible use in reapportionment.     

Soft Null Hypotheses: A Case Study of Image Enhancement Detection in Brain Lesions

This work is motivated by a study of a population of multiple sclerosis (MS) patients using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) to identify active brain lesions. At each visit, a contrast agent is administered intravenously to a subject and a series of images are acquired to reveal the location and activity of MS lesions within the brain. Our goal is to identify the enhancing lesion locations at the subject level and lesion enhancement patterns at the population level. We analyze a total of 20 subjects scanned at 63 visits (～30Gb), the largest population of such clinical brain images. After addressing the computational challenges, we propose possible solutions to the difficult problem of transforming a qualitative scientific null hypothesis, such as “this voxel does not enhance,” to a well-defined and numerically testable null hypothesis based on the existing data. We call such procedure “soft null” hypothesis testing as opposed to the standard “hard null” hypothesis testing. This problem is fundamentally different from: (1) finding testing statistics when a quantitative null hypothesis is given; (2) clustering using a mixture distribution; or (3) setting a reasonable threshold with a parametric null assumption. Supplementary materials are available online.     

A Case Study of Stochastic Optimization in Health Policy: Problem Formulation and Preliminary Results

We use Bayesian decision theory to address a variable selection problem arising in attempts to indirectly measure the quality of hospital care, by comparing observed mortality rates to expected values based on patient sickness at admission. Our method weighs data collection costs against predictive accuracy to find an optimal subset of the available admission sickness variables. The approach involves maximizing expected utility across possible subsets, using Monte Carlo methods based on random division of the available data into N modeling and validation splits to approximate the expectation. After exploring the geometry of the solution space, we compare a variety of stochastic optimization methods –- including genetic algorithms (GA), simulated annealing (SA), tabu search (TS), threshold acceptance (TA), and messy simulated annealing (MSA) –- on their performance in finding good subsets of variables, and we clarify the role of N in the optimization. Preliminary results indicate that TS is somewhat better than TA and SA in this problem, with MSA and GA well behind the other three methods. Sensitivity analysis reveals broad stability of our conclusions.     

Extreme Value Analysis of a Large Designed Experiment: A Case Study in Bulk Carrier Safety

The bulk carrier M.V. Derbyshire sank in 1980 when she encountered a typhoon near Japan. The most likely cause of her loss was finally explained in the report of the Re-opened Formal Investigation in 2000. The report also revealed inadequacies in safety standards for such vessels, particularly concerning regulations governing hatch cover strengths, and requested further work be undertaken to examine the sufficiency of aspects of the existing international standards for ship design. This paper describes the extreme value analysis of data from a large designed experiment intended to aid the revision of these safety standards. We highlight the importance of consistency of results over the different conditions examined, and how this can be achieved using various data pooling and regression techniques.     

老库区生态型反贫困决策分析—以四川省大洪河水库邻水县库区为例

我国老库区面临着严重的贫困和生态环境双重问题,而其贫困为典型的环境制约型贫困,贫困与生态环境问题交织在一起,互为因果.对于典型环境制约型贫困的老库区,只有打破贫困与生态环境之间的恶性循环,建立社会、经济和生态环境之间的良性循环才是老库区反贫困的根本途径.本研究以四川省大洪河水库邻水县库区为例,在对老库区反贫困与生态环境可持续性进行分析的基础上,采用不确定多目标规划方法,构建了四川省大洪河水库邻水县库区的生态型反贫困规划模型.通过系统分析和建立规划模型,既定性又定量地进行了四川省大洪河水库邻水县库区反贫困和生态环境可持续性研究,就整个邻水县库区而言,需进行移民8711人,新修梯田3188.24hm2,扩建经济林果园地1413.09hm2,新建人工草地85.47hm2,才有可能达到反贫困和提高生态环境可持续性的目标.     

封闭空间中新型冠状病毒肺炎传播模型:以日本“钻石公主号”邮轮为例

该文以新型冠状病毒(SARS-Cov-2)在日本钻石公主号邮轮上传播为例,通过建立简单的易感者-感染者传染病模型,研究在封闭空间中新冠病毒肺炎(COVID-19)的传播机制.动力学分析和数值拟合预测了疾病传播过程和最终结果,讨论了不同隔离措施对疾病传播进程的影响,并给出防控策略建议.     

区域农业循环经济发展评价——以安徽省临泉县为例

本文尝试应用建立在AHP方法基础上的农业循环经济基础评价和发展障碍度诊断对区域农业循环经济发展进行评价,其中障碍度诊断又分为单项障碍度诊断和分类障碍度诊断。用此方法本文对临泉县以黄牛为纽带、工农牧综合发展的农业循环经济模式和依托农业专业技术协会推广循环经济的县域农业循环经济进行了评价。