Dynamic principal component analysis with missing values

Dynamic principal component analysis (DPCA), also known as frequency domain principal component analysis, has been developed by Brillinger [Time Series: Data Analysis and Theory, Vol. 36, SIAM, 1981] to decompose multivariate time-series data into a few principal component series. A primary advantage of DPCA is its capability of extracting essential components from the data by reflecting the serial dependence of them. It is also used to estimate the common component in a dynamic factor model, which is frequently used in econometrics. However, its beneficial property cannot be utilized when missing values are present, which should not be simply ignored when estimating the spectral density matrix in the DPCA procedure. Based on a novel combination of conventional DPCA and self-consistency concept, we propose a DPCA method when missing values are present. We demonstrate the advantage of the proposed method over some existing imputation methods through the Monte Carlo experiments and real data analysis.     

Period analysis of variable stars by robust smoothing

Summary.  The objective is to estimate the period and the light curve (or periodic function) of a variable star. Previously, several methods have been proposed to estimate the period of a variable star, but they are inaccurate especially when a data set contains outliers. We use a smoothing spline regression to estimate the light curve given a period and then find the period which minimizes the generalized cross-validation (GCV). The GCV method works well, matching an intensive visual examination of a few hundred stars, but the GCV score is still sensitive to outliers. Handling outliers in an automatic way is important when this method is applied in a 'data mining' context to a vary large star survey. Therefore, we suggest a robust method which minimizes a robust cross-validation criterion induced by a robust smoothing spline regression. Once the period has been determined, a nonparametric method is used to estimate the light curve. A real example and a simulation study suggest that the robust cross-validation and GCV methods are superior to existing methods.     

Tests for the order of integration against higher order integration

Locally best invariant tests for the null hypothesis of I(p) against the alternative hypothesis of I(q), < q, are developed for models with independent normal errors. The tests are semiparametrically extended for models with autocorrelated errors. The method is illustrated by two real data sets in terms of double unit roots. The proposed tests can be used for determining integration orders of nonstationary time series.     

Individual performance as a multidimensional construct: a test of construct validity

While much of the extant literature in public management has focused on individual performance using only in-role or job performance, there is a need to consider another approach to individual performance, one that includes extra-role performance. However, public sector organizations have rarely emphasized the integration of these two types of behavioral performance to measure individual performance. Using confirmatory factor analysis and other statistical analyses, this study examines the construct validity of a multidimensional measure of individual performance. This analysis supports a multidimensional approach to individual performance. The implications and limitations of the findings are discussed.     

A Bayesian approach to assessing population bioequivalence in a 2 ×2 crossover design

A Bayesian testing procedure is proposed for assessment of the bioequivalence in both mean and variance, which ensures population bioequivalence under the normality assumption. We derive the joint posterior distribution of the means and variances in a standard 2 ×2 crossover experimental design and propose a Bayesian testing procedure for bioequivalence based on a Markov chain Monte Carlo method. The proposed method is applied to a real data set.     

Teaching and Providing Recovery-oriented Care Through Problem-posing Dialogue

As the recovery paradigm proliferates throughout systems of mental health care, social workers are being required to provide recovery-oriented services. Yet there has been little discussion about what changes need to be made in social work education to produce recovery-oriented social workers. This article uses Paulo Freire's theory of pedagogy to help social work educators understand how they can develop problem-posing relationships with their students in order to teach students about the relationships that social workers ought to have with people in recovery.     

Incoterms(国贸术语解释通则)序言上的问题和修正方案

在经过修订的1990通则的基础上形成的Incoterms 2000由13个部分构成,是考虑到自由关税区的扩大、商业交易中电子通信方式使用范围的扩大、运输惯例的变化等,根据流通中不能运输文件活用的增加和多种运输技法的变化,以Incoterms1990为基础进行修正的,因此反映了现有国际贸易惯例,是对比今后相当长的时期的修正.尽管如此,和其它的法则一样,不能涉及所有需要管理的内容.Incoterms 2000的绪论部分在对通则的解释中起到重要引导作用,它由22个项目组成的,通过此绪论我们提出了若干的问题.本论文提出了关于这些问题的修正方案,目的是给予商业界和学界对Incoterms 2000理解上的帮助,希望对Incoterms 2000通则日后的修订有所指导和展望.     

韩国吸引中国游客的战略和方案

中国经济的持续增长,使新兴富豪和高收入阶层的人数不断扩大,从而成为对韩国极具吸引力的市场。本研究将就中国市场的潜在旅游需求进行评价,对中国游客对韩国的印象进行调查,并提出韩国吸引中国游客的战略和具体方案。     

On change point test for ARMA–GARCH models: Bootstrap approach

The problem of testing for a parameter change has been a core issue in time series analysis. It is well known that the estimates-based CUSUM test often suffers from severe size distortions in general GARCH type models. The residual-based CUSUM test has been used as an alternative, which, however, has a defect not to detect the ARMA parameter changes in ARMA–GARCH models. As a remedy, one can employ the score vector-based CUSUM test in ARMA–GARCH models as in Oh and Lee (0000). However, it shows some size distortions for relatively small samples. Hence, we consider the bootstrap counterpart for obtaining a more stable test. Focus is made on the verification of the weak consistency of the proposed test. An empirical study is illustrated for its evaluation.