A Regression Model for the AUC of Clustered Ordinal Test Results and Working Independent Optimal Weights

We study a regression model on the area under the receiver operating characteristic curves (AUC) for clustered (or repeatedly measured) test results. To account for cluster information, we consider a weighted estimating equation for Dodd and Pepe (2003 Dodd , L. , Pepe , M. ( 2003 ). Semiparametric regression for the area under the receiver operating charateristic curve . Journal of the American Statistical Association 98 : 409 – 417 .[Taylor & Francis Online], [Web of Science ®] , [Google Scholar])'s regression model with working independence weights. We find the optimal weight in the given class of working independence weights to minimize the variance (or MSE) of regression estimators. We apply the proposed procedure to analyzing our recent experiment on diagnosing a liver disorder. In this experiment, we investigated MRI images of patients having symptoms of potential liver disorder to compare the performance of different MRI picturing methods in testing for liver disorders.     

The Synthetic Mean Square Error Control Chart

A synthetic mean square error (MSE) control chart is presented in this study for monitoring the changes in the mean and standard deviation of a normally distributed process. The synthetic MSE control chart is a combination of the standard MSE control chart and the conforming run length (CRL) control chart. From the numerical comparisons, the synthetic MSE control chart is always more efficient than the standard MSE control chart in detecting shifts in the process mean and standard deviation. The synthetic MSE chart also performs better than the exponentially weighted moving average-semicircle (EWMA-SC) chart, except for some cases where the process mean shifts are small.     

Elicitation of health values from mortality risk reduction

There are concerns regarding uncertainty about the accuracy of applying available empirical willingness-to-pay (WTP) estimates for reducing accidental deaths to value changes in risks of pollution-related deaths. In this study, we develop a theoretical model on defining WTP, and its determinants, and derive WTP estimates for changes in pollution-related mortality risks with varying morbidity and timing attributes. A survey is designed and conducted with 100 subjects. Each subject was to complete five choice sets and provided a range of implicit values of statistical life (VSL). The choices are estimated using the logit procedure. And, using the results of estimated multinomial logit model, the VSL is estimated to about $6.2 million.     

Socioeconomic Differences in the Health of Black Union Army Soldiers

This paper investigates patterns of socioeconomic difference in the wartime morbidity and mortality of black Union Army soldiers. Among the factors that contributed to a lower probability of contracting and dying from diseases were (1) lighter skin color, (2) a non-field occupation, (3) residence on a large plantation, and (4) residence in a rural area prior to enlistment. Patterns of disease-specific mortality and timing of death suggest that the differences in the development of immunity against diseases and in nutritional status prior to enlistment were responsible for the observed socioeconomic differences in wartime health. For example, the advantages of light-skinned soldiers over dark-skinned and of enlisted men formerly engaged in non-field occupations over field hands resulted from differences in nutritional status. The lower wartime mortality of ex-slaves from large plantations can be explained by their better-developed immunity as well as superior nutritional status. The results of this paper suggest that there were substantial disparities in the health of the slave population on the eve of the Civil War.     

Testing for Stochastic Monotonicity

We propose a test of the hypothesis of stochastic monotonicity. This hypothesis is of interest in many applications in economics. Our test is based on the supremum of a rescaled U‐statistic. We show that its asymptotic distribution is Gumbel. The proof is difficult because the approximating Gaussian stochastic process contains both a stationary and a nonstationary part, and so we have to extend existing results that only apply to either one or the other case. We also propose a refinement to the asymptotic approximation that we show works much better in finite samples. We apply our test to the study of intergenerational income mobility.     

A general method to determine sampling windows for nonlinear mixed effects models with an application to population pharmacokinetic studies

Optimal design methods have been proposed to determine the best sampling times when sparse blood sampling is required in clinical pharmacokinetic studies. However, the optimal blood sampling time points may not be feasible in clinical practice. Sampling windows, a time interval for blood sample collection, have been proposed to provide flexibility in blood sampling times while preserving efficient parameter estimation. Because of the complexity of the population pharmacokinetic models, which are generally nonlinear mixed effects models, there is no analytical solution available to determine sampling windows. We propose a method for determination of sampling windows based on MCMC sampling techniques. The proposed method attains a stationary distribution rapidly and provides time-sensitive windows around the optimal design points. The proposed method is applicable to determine sampling windows for any nonlinear mixed effects model although our work focuses on an application to population pharmacokinetic models.     

Measuring open source software success

Since the mid-1990s, there has been a surge of interest among academics and practitioners in open source software (OSS). While there is an abundance of literature on OSS, most studies on OSS success are either qualitative or exploratory in nature. To identify the factors that influence OSS success and establish generalizability, an empirical study measuring OSS success would enable OSS developers and users to improve OSS usage. In this study, we develop an OSS success model from a previous Information Systems success model incorporating the characteristics of OSS. Using the proposed model, we identify five determinants for OSS success as well as a number of significant relationships among these determinants. Our findings demonstrate that software quality and community service quality have significant effects on user satisfaction. Software quality and user satisfaction, in turn, have significant effects on OSS use. Additionally, OSS use and user satisfaction have significant effects on individual net benefits. This research contributes towards advancing theoretical understanding of OSS success as well as offering OSS practitioners for enhancing OSS success.     

Does what happens in group care stay in group care? The relationship between problem behaviour trajectories during care and post‐placement functioning

Residential programmes for youth may improve youth behaviour during placement, but it is not clear whether there is an association between a youth's behaviour pattern during placement and post‐placement outcomes. Life course perspective has been used to understand longitudinal patterns and pathways, and new statistical methods have been developed to identify latent trajectory groups. This study used administrative data from a family‐style group care programme to assess whether a youth's externalizing behaviour trajectory while in placement can significantly predict delinquency and adjustment outcomes at discharge and 6‐month follow‐up. Findings from multinomial logistic regression revealed a statistically significant relationship between a youth's behaviour trajectory class and outcomes. Behaviour pattern during care was a stronger predictor of outcome than cross‐sectional measures such as other demographic factors, placement history or mental‐health need indicators.     

儒学知识化与现代学术

近年来,中文学术界不时出现一种声音,批判现代儒学知识化的趋势。不少人强调:传统儒学是一套关于生命的学问,而不只是一套知识系统;它是一套整体的学问,无法被纳入现代的学科分类之中。他们忧虑:在现代西方的学术体制中,传统儒学会被割裂,因而丧失其主体性与生命力。在有关中国哲学的合法性(正当性)之争论中,也不时冒出这类的声音。这种忧虑自有其道理,但亦有其盲点。因为传统学术的专业化不仅是中国传统,也是西方传统(如西方神学)所要面对的问题。现代学术体制的形成有其历史背景,它固然有所遮蔽,亦有所开显。将传统儒学纳入现代学术体制而知识化,固然有所失,但亦有所得,因为这可以开启儒学对现代社会的批判功能。