ROC Curves in Non‐Parametric Location‐Scale Regression Models

Abstract. The receiver operating characteristic (ROC) curve is a tool of extensive use to analyse the discrimination capability of a diagnostic variable in medical studies. In certain situations, the presence of a covariate related to the diagnostic variable can increase the discriminating power of the ROC curve. In this article, we model the effect of the covariate over the diagnostic variable by means of non‐parametric location‐scale regression models. We propose a new non‐parametric estimator of the conditional ROC curve and study its asymptotic properties. We also present some simulations and an illustration to a data set concerning diagnosis of diabetes.     

地理教育的现状与改革的思考

高考文科取消地理科目后，中学地理教育及高师地理教育均受到冲击，但地理科学的特殊地位决定了它是不可能被取代的．地理科学的发展应在应用方面找出路，并不断深化地理教育改革．     

Modified Wald statistics for generalized linear models

Summary: Wald statistics in generalized linear models are asymptotically ² distributed. The asymptotic chi–squared law of the corresponding quadratic form shows disadvantages with respect to the approximation of the finite–sample distribution. It is shown by means of a comprehensive simulation study that improvements can be achieved by applying simple finite–sample size approximations to the distribution of the quadratic form in generalized linear models. These approximations are based on a ² distribution with an estimated degree of freedom that generalizes an approach by Patnaik and Pearson. Simulation studies confirm that nominal level is maintained with higher accuracy compared to the Wald statistics.     

边界Logistic违约率模型及实证研究

在前人研究基础上对边界Logistic违约率模型展开进一步研究.首先通过抽样分布性质的研究从理论上说明了为什么边界Logistic违约率模型更优越.然后利用中国公司数据展开实证研究,不仅找到了Cramer问题的中国证据,同时还发现边界Logistic违约率模型不仅能够克服Cramer问题、而且对临界值不敏感、同时预测效率也相对较高.     

Book Reviews

This article examines some difficulties associated with the Haynes–Stone model and attempts to clarify how the model can be justified as representing the hypothesis that “quantity is demand determined and price is supply determined.” It also argues that the applications of such a model as was done by Haynes and Stone might not have resolved the controversies related to the Phillips curve and the supply function of exports (or imports).     

论代理契约中决策方案的设计与选择

本文论述了以博奕关系简化复杂的代理关系,用必然等值评估代理人的优先选择曲线,根据代理人优先选择曲线的类型,分析代理人的风险态度,据以设计相应的激励方案的方法与过程.     

Analysis of the Bovine Spongiform Encephalopathy Maternal Cohort Study: the Discordant Case–Control Pairs

The progeny of the affected and non-affected dams in the bovine spongiform encephalopathy (BSE) cohort study were paired in terms of their farm of origin and approximate date of birth. This paper presents an exact logistic regression analysis that avoids modelling the differences between the pairs and so analyses only the discordant pairs. There is some evidence that the pairs in which the affected animal was born to the affected dam tend to be those in which the onset of BSE in the affected dam preceded or occurred soon after the calving. This suggests some occurrence of maternal transmission.     

A comparison of classification models to identify the Fragile X Syndrome

The main models of machine learning are briefly reviewed and considered for building a classifier to identify the Fragile X Syndrome (FXS). We have analyzed 172 patients potentially affected by FXS in Andalusia (Spain) and, by means of a DNA test, each member of the data set is known to belong to one of two classes: affected, not affected. The whole predictor set, formed by 40 variables, and a reduced set with only nine predictors significantly associated with the response are considered. Four alternative base classification models have been investigated: logistic regression, classification trees, multilayer perceptron and support vector machines. For both predictor sets, the best accuracy, considering both the mean and the standard deviation of the test error rate, is achieved by the support vector machines, confirming the increasing importance of this learning algorithm. Three ensemble methods - bagging, random forests and boosting - were also considered, amongst which the bagged versions of support vector machines stand out, especially when they are constructed with the reduced set of predictor variables. The analysis of the sensitivity, the specificity and the area under the ROC curve agrees with the main conclusions extracted from the accuracy results. All of these models can be fitted by free R programs.     

基于环境学习曲线的山东省SO2排放及节能减排潜力分析

基于1981—2006年的数据对山东省SO2排放的规律进行研究，得到山东省SO2排放的环境学习曲线。应用这一曲线，定量分析山东省17个地级市减少SO2排放的潜力，并结合2006年各市的万元GDP能耗情况，对它们的节能减排潜力进行综合评价。     

儿童拼图性识字的记忆研究

以艾宾浩斯的遗忘曲线为基本框架,通过拼图性学习和常规性学习两种不同学习生字方法的实验比较,对儿童识字的一般性规律进行研究。得到结论:拼图性识字在记忆的保持上优于常规性识字;拼图性识字在学习有笔画难度的字上优于常规性识字;拼图性识字同样符合艾宾浩斯的遗忘曲线规律。拼图性识字教学符合儿童以动作思维为主的认识特点,符合儿童心理的年龄特征,能提高对字形记忆的效果,让儿童可以有效、有趣、自主进行早期识字学习。