Oracle properties of SCAD-penalized support vector machine

In many scientific investigations, a large number of input variables are given at the early stage of modeling and identifying the variables predictive of the response is often a main purpose of such investigations. Recently, the support vector machine has become an important tool in classification problems of many fields. Several variants of the support vector machine adopting different penalties in its objective function have been proposed. This paper deals with the Fisher consistency and the oracle property of support vector machines in the setting where the dimension of inputs is fixed. First, we study the Fisher consistency of the support vector machine over the class of affine functions. It is shown that the function class for decision functions is crucial for the Fisher consistency. Second, we study the oracle property of the penalized support vector machines with the smoothly clipped absolute deviation penalty. Once we have addressed the Fisher consistency of the support vector machine over the class of affine functions, the oracle property appears to be meaningful in the context of classification. A simulation study is provided in order to show small sample properties of the penalized support vector machines with the smoothly clipped absolute deviation penalty.     

SiZer analysis for the comparison of time series

SiZer (SIgnificant ZERo crossing of the derivatives) is a scale-space visualization tool for statistical inferences. In this paper we introduce a graphical device, which is based on SiZer, for the test of the equality of the mean of two time series. The estimation of the quantile in a confidence interval is theoretically justified by advanced distribution theory. The extension of the proposed method to the comparison of more than two time series is also done using residual analysis. A broad numerical study is conducted to demonstrate the sample performance of the proposed tool. In addition, asymptotic properties of SiZer for the comparison of two time series are investigated.     

Overweight Korean Adolescents and Academic Achievement

The relationship between academic achievement and being overweight among South Korean high school students was examined. Data used in the regression were from the Korean Education and Employment Panel Survey. The theoretical framework that poor school performance increases the risk of adolescents’ being overweight, which, in turn, causes poor school performance, was supported. With no other direct or indirect association between weight and achievement, an overweight high school student’s poor performance in school was assumed to be a function of the psychosocial well-being variables and self-concern about weight. A simultaneous-equation regression model that endogenized the likelihood an individual is classified as overweight (a binary variable) and the performance of that individual on the College Scholastic Ability Test (CSAT) incorporates the unobserved psychosocial well-being correlated with both school grades and being overweight.

The fatal affinity of the ‘Sonderweg’ revisited: The diffusion of emergency powers in Germany,Japan and Korea (1871–1987)

Many authoritarian regimes in Asia have utilized emergency powers to legitimize their measures of suppressing political opponents and maintaining power. In opposition to previous interpretations that categorize Asian experiences as ‘exceptional cases’ when compared to ‘normal’ Western liberal democracies, this article suggests that this issue should be viewed within the context of the broader ‘affinity’ of the ‘Sonderweg’ phenomenon. The paper compares Germany, Japan and Korea by examining the complex ‘diffusion’ processes of constitutional emergency powers and also by illuminating systemic affinities and fundamental differences. It argues that elites and technocrats in Germany, Japan and Korea exhibited diverging patterns in adopting, filtering and utilizing these constitutional powers.     

Bridging the territorial divide: immigrants’ cross-border communication and the spatial dynamics of their kin networks

The transnational perspective emphasises the persistence of immigrants’ home country connections, yet existing research adds little to our understanding of the mechanisms by which cross-border ties are maintained. We use nationally representative data of immigrants in Spain to describe changes in their kin network and study how two characteristics, migration stage (whether kin already resided in Spain at the time of emigration and whether any kin remained in the birth country (BC) at the time of interview) and relationship-specific locations of kin (children, parents, spouse, siblings), influence the frequency of cross-border communication. We find an expansion in the total number of kin largely due to childbearing and marriage. The average fraction of migrants’ immediate kin in Spain shifts from 6% to 41%. The presence of at least one kin in the BC increases the frequency of cross-border communication, but with the exception of siblings, the presence of family already in Spain at the time of emigration does not. Siblings and parents were far more likely to retain a BC presence, but they were less likely than spouses or children to be contacted daily. While these ties are generally long-lasting, communication wanes as immigrant embeddedness in the receiving country grows.     

Stressful and positive experiences of women who served in Vietnam

Experiences of women who served during the Vietnam War have been described in interviews/anecdotal reports but rarely in empirical literature. Potential positive (versus negative) aspects of service or its impact on well-being are seldom considered. We describe stressful and positive experiences reported by approximately 1,300 female military personnel, Red Cross workers, and others deployed to Vietnam. Prominent stressful (e.g., negative living/working conditions) and positive (e.g., interpersonal relationships) themes and differences based on trauma history, Vietnam experiences, and group membership are explored. We evaluate associations between themes and psychological well-being. Findings provide insight into experiences of this understudied group of women.     

Laplace based approximate posterior inference for differential equation models

Ordinary differential equations are arguably the most popular and useful mathematical tool for describing physical and biological processes in the real world. Often, these physical and biological processes are observed with errors, in which case the most natural way to model such data is via regression where the mean function is defined by an ordinary differential equation believed to provide an understanding of the underlying process. These regression based dynamical models are called differential equation models. Parameter inference from differential equation models poses computational challenges mainly due to the fact that analytic solutions to most differential equations are not available. In this paper, we propose an approximation method for obtaining the posterior distribution of parameters in differential equation models. The approximation is done in two steps. In the first step, the solution of a differential equation is approximated by the general one-step method which is a class of numerical numerical methods for ordinary differential equations including the Euler and the Runge-Kutta procedures; in the second step, nuisance parameters are marginalized using Laplace approximation. The proposed Laplace approximated posterior gives a computationally fast alternative to the full Bayesian computational scheme (such as Makov Chain Monte Carlo) and produces more accurate and stable estimators than the popular smoothing methods (called collocation methods) based on frequentist procedures. For a theoretical support of the proposed method, we prove that the Laplace approximated posterior converges to the actual posterior under certain conditions and analyze the relation between the order of numerical error and its Laplace approximation. The proposed method is tested on simulated data sets and compared with the other existing methods.     

Trajectories of Community-Based Service Use: The Importance of Poverty and Living Arrangements

ABSTRACT

This study examined how older adults’ living arrangements and poverty status affected their use of in-home health, functional, and out-of-home services over time. Using eight waves of data from the Korea Welfare Panel Study, we employed a logistic mixed-effect model to analyze how poverty and living arrangements affect community-based service use. Living-alone older adults and elder-only couples were more likely than co-residing households to use services. Elder-only couples, when poor, were more likely to use in-home and out-of-home services over time. Understanding predictors of community-based service use over time enables researchers and policymakers to better understand the process of aging-in-place.