Comparison of Scoring Systems for Invasive Pests Using ROC Analysis and Monte Carlo Simulations

Different international plant protection organisations advocate different schemes for conducting pest risk assessments. Most of these schemes use structured questionnaire in which experts are asked to score several items using an ordinal scale. The scores are then combined using a range of procedures, such as simple arithmetic mean, weighted averages, multiplication of scores, and cumulative sums. The most useful schemes will correctly identify harmful pests and identify ones that are not. As the quality of a pest risk assessment can depend on the characteristics of the scoring system used by the risk assessors (i.e., on the number of points of the scale and on the method used for combining the component scores), it is important to assess and compare the performance of different scoring systems. In this article, we proposed a new method for assessing scoring systems. Its principle is to simulate virtual data using a stochastic model and, then, to estimate sensitivity and specificity values from these data for different scoring systems. The interest of our approach was illustrated in a case study where several scoring systems were compared. Data for this analysis were generated using a probabilistic model describing the pest introduction process. The generated data were then used to simulate the outcome of scoring systems and to assess the accuracy of the decisions about positive and negative introduction. The results showed that ordinal scales with at most 5 or 6 points were sufficient and that the multiplication‐based scoring systems performed better than their sum‐based counterparts. The proposed method could be used in the future to assess a great diversity of scoring systems.     

An application of lomax distributions in receiver operating characteristic(roc)curve analysis

Receiver operating characteristic(ROC)curves are useful for studying the performance of diagnostic tests. ROC curves occur in many fields of applications including psychophysics, quality control and medical diagnostics. In practical situations, often the responses to a diagnostic test are classified into a number of ordered categories. Such data are referred to as ratings data. It is typically assumed that the underlying model is based on a continuous probability distribution. The ROC curve is then constructed from such data using this probability model. Properties of the ROC curve are inherited from the model. Therefore, understanding the role of different probability distributions in ROC modeling is an interesting and important area of research. In this paper the Lomax distribution is considered as a model for ratings data and the corresponding ROC curve is derived. The maximum likelihood estimation procedure for the related parameters is discussed. This procedure is then illustrated in the analysis of a neurological data example.     

Validation of qualitative microbiological test methods

This paper considers a statistical model for the detection mechanism of qualitative microbiological test methods with a parameter for the detection proportion (the probability to detect a single organism) and a parameter for the false positive rate. It is demonstrated that the detection proportion and the bacterial density cannot be estimated separately, not even in a multiple dilution experiment. Only the product can be estimated, changing the interpretation of the most probable number estimator. The asymptotic power of the likelihood ratio statistic for comparing an alternative method with the compendial method, is optimal for a single dilution experiment. The bacterial density should either be close to two CFUs per test unit or equal to zero, depending on differences in the model parameters between the two test methods. The proposed strategy for method validation is to use these two dilutions and test for differences in the two model parameters, addressing the validation parameters specificity and accuracy. Robustness of these two parameters might still be required, but all other validation parameters can be omitted. A confidence interval‐based approach for the ratio of the detection proportions for the two methods is recommended, since it is most informative and close to the power of the likelihood ratio test. Copyright © 2014 John Wiley & Sons, Ltd.     

Simultaneous inference of a misclassified outcome and competing risks failure time data

Ipsilateral breast tumor relapse (IBTR) often occurs in breast cancer patients after their breast conservation therapy. The IBTR status' classification (true local recurrence versus new ipsilateral primary tumor) is subject to error and there is no widely accepted gold standard. Time to IBTR is likely informative for IBTR classification because new primary tumor tends to have a longer mean time to IBTR and is associated with improved survival as compared with the true local recurrence tumor. Moreover, some patients may die from breast cancer or other causes in a competing risk scenario during the follow-up period. Because the time to death can be correlated to the unobserved true IBTR status and time to IBTR (if relapse occurs), this terminal mechanism is non-ignorable. In this paper, we propose a unified framework that addresses these issues simultaneously by modeling the misclassified binary outcome without a gold standard and the correlated time to IBTR, subject to dependent competing terminal events. We evaluate the proposed framework by a simulation study and apply it to a real data set consisting of 4477 breast cancer patients. The adaptive Gaussian quadrature tools in SAS procedure NLMIXED can be conveniently used to fit the proposed model. We expect to see broad applications of our model in other studies with a similar data structure.     

所有权、市场竞争及人力资本专用性——一个模型的建立及扩展

建立了"剩余控制权与剩余索取权相互关系"模型,认为剩余控制权是连接产权与市场的中介,并通过人力资本专用性对剩余控制权的影响把当事人的工作特征纳入视野。     

Functional specificity in discussion networks: The influence of general and problem-specific networks on health outcomes

Though commonly used in social science research to measure the influence of social networks, the link between discussing “important matters” within networks and the achievement of instrumental ends is frequently unspecified or untested. To address this gap, we explore the consequences of using the general “important matters” approach versus one in which the substance of discussions is directly linked to the outcomes of interest. The egocentric social networks of people experiencing an acute health crisis are examined. We identify the characteristics of and the degree of membership overlap between “important matters” and “health matters” discussants, and explore their relative power in explaining a wide range of health and health services-related outcomes. We find no evidence for the influence of “important matters” networks, while characteristics of “health matters” networks demonstrate a significant effect across all models.     

西欧的"独特性"、"东方专制主义"与近代法治

文章认为,法治的生成和发展是与国家和市民社会关系紧密相关的,而国家和市民社会关系在东西方却具有不同的演进路径.即在西方呈现的是国家与市民社会相复合(古希腊)--国家对市民社会的监护(古罗马)--国家吞并市民社会(西欧中世纪)--市民社会与国家的二元分立和抗衡(近代资本主义).这种发展路径造成了多元文化和权利抗衡国家权力的西欧"独特性",并促动了近代法治的生成.而古中国及东方国家则一直处于国家吞并市民社会状态,形成了扼制权利和自由的"东方专制主义",法治便无以产生.这启示我们,中国要走向法治,就不应仅满足于法律制度的植入和法律体系的建构,也不应满足于民主政治、市场经济和理性文化这种"法治基础和条件"的一般性解说,而应着力建立国家和市民社会的良性互动关系,这才是问题的关键.     

Screening for depression after cardiac events using the Beck Depression Inventory-II and the Geriatric Depression Scale

Despite findings that depression is a risk factor for heart disease and for death following cardiac events and that depressed cardiac patients experience significantly reduced quality of life and are less likely to follow treatment regimens, depression is neither adequately identified nor treated in cardiac patients. Recent calls in the literature for the use of standardized screening measures and sensitivity/specificity studies to identify useful measures compelled us to examine the sensitivity and specificity of the Beck Depression Inventory-II (BDI-II) and Geriatric Depression Scale (GDS) and recommend appropriate cut-scores for identifying depression in post-myocardial infarction or unstable angina patients. A total of 119 patients who met criteria for either acute myocardial infarction or unstable angina pectoris were recruited from coronary care units at three hospitals and interviewed in their homes approximately 2 weeks post-admission. The criterion used in the study was the Structured Clinical Interview for DSM-IV-TR Axis I Disorders (SCID-I/NP). Administration of the SCID-I/NP, BDI-II, and GDS was counterbalanced using a digram-balanced approach and blinded comparison was used. Alphas were .89 for BDI-II and .88 for GDS. For major depression, a BDI-II cut-score of 10 produced a sensitivity = 100%, specificity = 75%, and PPV = 18% whereas a GDS cut-score of 14 produced sensitivity = 100%, specificity = 94%, and PPV = 50%. For major/double depression, a BDI-II cut-score of 10 produced sensitivity = 100%, specificity = 75%, and PPV = 21% whereas a GDS cut-score of 13 produced sensitivity = 100%, specificity = 91%, and PPV = 41%. Although both measures demonstrated excellent reliability and sensitivity, the GDS showed better specificity and PPV and is recommended as the better screen for major depression or double depression with cardiac patients.     

论诗歌翻译的详略度——以李白三首诗歌英译为例

文章以认知语言学有关详略度的研究为理论框架,通过分析对比李白诗歌《送友人》、《月下独酌》和《长干行》的不同英译文本,探讨了详略度对诗歌翻译的制约。研究发现译者在翻译过程中都自觉或不自觉地受到了原诗详略度的制约,而且译者应尽量实现与原诗的"详略度"对等。