Confidence Intervals for the Youden Index and Corresponding Optimal Cut-Point

A global measure of biomarker effectiveness is the Youden index, the maximum difference between sensitivity, the probability of correctly classifying diseased individuals, and 1-specificity, the probability of incorrectly classifying healthy individuals. The cut-point leading to the index is the optimal cut-point when equal weight is given to sensitivity and specificity. Using the delta method, we present approaches for estimating confidence intervals for the Youden index and corresponding optimal cut-point for normally distributed biomarkers and also those following gamma distributions. We also provide confidence intervals using various bootstrapping methods. A comparison of interval width and coverage probability is conducted through simulation over a variety of parametric situations. Confidence intervals via delta method are shown to have both closer to nominal coverage and shorter interval widths than confidence intervals from the bootstrapping methods.     

治理机制的适应性研究

机会主义行为假设是交易成本经济学治理机制的根本性行为假设之一,而专用性资产是治理结构选择的重要维度.当资产专用性很强时,内部组织比市场组织更有优势.利用要挟与反要挟双方博弈,最终促使要挟方履约的机制,得到了克莱因的强调.     

西南民族地区出生人口性别比问题论析

西南民族地区在五普时即已出现出生人口性别比失调现象,这是继该地区人口数量、人口素质、人口贫困等问题尚未完全解决而又出现的人口问题。这一问题已经和可能将要产生的负面效应无疑会对西南民族地区社会经济的健康发展、人口安全环境建构、社会稳定和边疆安全等产生严重影响。同时又因区域文化、生境等客观存在,其失调特征与原因有着比汉族地区更多的特殊性。     

从品牌个性角度论农产品品牌结构塑造方法

农产品品牌建设中,品牌个性对品牌结构起到了导向性作用。品牌个性偏重"仁"智"雅"时,采取单一品牌结构模式较好;品牌个性偏重"勇"乐"时,采取多品牌结构模式较为适宜。农产品品牌不同于普通商品品牌的特点众多,绿色、环保、地理保护、有机等概念都在左右着品牌个性的塑造,品牌结构设置因此要更多的考虑这些品牌的个性特点,在此基础上建立起来的品牌结构才更科学。     

On the confusion matrix in credit scoring and its analytical properties

Abstract

Confusion Matrix is an important measure to evaluate the accuracy of credit scoring models. However, the literature about Confusion Matrix is limited. The analytical properties of Confusion Matrix are ignored. Moreover, the concept of Confusion Matrix is confusing. In this article, we systematically study Confusion Matrix and its analytical properties. We enumerate 16 possible variants of Confusion Matrix and show that only 8 are reasonable. We study the relationship between Confusion Matrix and 2 other performance measures: the receiver operating characteristic curve (ROC) and Kolmogorov-Smirnov statistic (KS). We show that an optimal cutoff score can be attained by KS.     

资产专用性、不确定性与水稻种植模式选择

从资产专用性与不确定性视角,运用二元Logistic模型实证分析了水稻种植模式选择的影响因素。研究结果表明：资产专用性与不确定性对水稻种植模式选择的影响,部分通过显著性检验;家庭中50岁以上务农劳动力越多、村庄交通条件越好,农户选择种植两季水稻的概率越低;务农劳动力兼业、拥有整地机械、灌溉条件越好,农户选择种植两季水稻的可能性更大,其中务农劳动力通过兼业使劳动时间错峰配置实现劳动力最优利用,最终使农户倾向于种植两季水稻。水田面积与稻农选择两季水稻种植模式呈现倒U型的关系;家庭务农劳动力人数、农业收入占比等控制变量对农户水稻种植模式选择的影响显著。政府应继续培育新型农业经营主体,发展适度规模经营,加大农机补贴力度,提高社会化服务水平,应对农业劳动力不足与弱质化的问题,提高农户种植两季水稻的积极性。     

Three optimal cut-point selection criteria based on sensitivity and specificity with user-defined weights

Methods: Based on the index S (S = SENSITIVITY (SEN) × SPECIFICITY (SPE)), the new weighted product index S_w is defined as S_w = (SEN)^2w × (SPE)^2(1-w), where (0≤w≤1). The S_w is developed to be a new tool to select the optimal cut point in ROC analysis and be compared with the other two commonly used criteria.

Results: Comparing the optimal cut point for the three criteria, the wave range of the optimal cut point for the maximized weighted Youden index criterion is the widest, the weighted closest-to-(0,1) criterion is the narrowest and the weighted product index S_w criterion lays between the ranges of the two criteria.     

论医患关系的法律属性

医患关系的法律属性问题是全部医事法学中最重要、最基本的问题，而我国法学界对该问题尚未达成共识，因而造成医疗纠纷处理上的司法混乱。本文拟从医患关系的基本属性、基本形态及其特殊性入手，着重分析医患关系的法律属性。     

Bayesian Interval Estimation for the Difference in TPRs and FPRs of Two Diagnostic Tests with Unverified Negatives

We derive Bayesian interval estimators for the differences in the true positive rates and false positive rates of two dichotomous diagnostic tests applied to the members of two distinct populations. The populations have varying disease prevalences with unverified negatives. We compare the performance of the Bayesian credible interval to the Wald interval using Monte Carlo simulation for a spectrum of different TPRs, FPRs, and sample sizes. For the case of a low TPR and low FPR, we found that a Bayesian credible interval with relatively noninformative priors performed well. We obtain similar interval comparison results for the cases of a high TPR and high FPR, a high TPR and low FPR, and of a high TPR and mixed FPR after incorporating mildly informative priors.     

详略度视域下的旅游文本翻译

本文着重从详略度视角，分析两个旅游文本的翻译，探讨如何充分利用详略度的不同来翻译旅游文本。