A change-point estimator with the hazard ratio

The problem of estimation of parameters in hazard rate change models with a change-point is considered. A change-point estimator using the hazard ratio is suggested and compared with the previously developed change-point estimators. The proposed estimator is shown to be consistent. The performance of the proposed estimator is checked and compared with other change-point estimators via simulation.     

Predictors of organizations’ crisis communication approaches: Full versus limited disclosure

This study investigates predictors of the public relations (full disclosure) versus legal (limited disclosure) approaches that may be used by organizations during a preventable crisis. Both tangible and intangible aspects of an organization were explored. The results reveal that degree of crisis preparation, public relations influences, and the perception of crisis as an opportunity were significant predictors that determine full versus limited disclosure selection.     

Promoting Constructive Conflict from a Conflict Transformation Perspective: The Case of Community-Based Collaboration in Korea

ABSTRACT

This article focuses on developing constructive conflict management in community-based collaborations for macro social workers. Using a conflict transformation perspective as a conceptual framework, we identified significant factors and their dynamic relationships in promoting constructive conflict in the context of 5 community-based collaborations in Korea. Hierarchical multiple regression analyses revealed that responsive coordination was a strong predictor of increased perceptions of constructive conflict. Further, a multiple mediator model indicated that open communication was indirectly associated with perceived constructive conflict by enhancing both equal decision-making and responsive coordination. We conclude by highlighting practical implications of our study.     

A Comparative Study of Semiparametric Estimation in Partially Linear Single-index Models

We consider a semiparametric method based on partial splines for estimating the unknown function and partially linear regression parameters in partially linear single-index models. Three methods—project pursuit regression (PPR), average derivative estimation (ADE), and a boosting method—are considered for estimating the single-index parameters. Simulations revealed that PPR with partial splines was superior in estimating single-index parameters, while the boosting method with partial splines performed no better than PPR and ADE. All three methods performed similarly in estimating the partially linear regression parameters. The relative performances of the methods are also illustrated using a real-world data example.     

Using the dependent wild bootstrap for the nonparametric goodness-of-fit test for density functions

In this paper, we consider the well-known nonparametric consistent model-specification test for the stationary density function (see [Aït-Sahalia Y. Testing continuous-time models of the spot interest rate. Rev Financ Stud. 1996;9:385–426; Li Q. Nonparametric testing of closeness between two unknown distribution functions. Econ Rev. 1996;15:261–274; Fan Y, Ullah A. On goodness-of-fit tests for weakly dependent processes using kernel method. J Nonparametric Stat. 2000;11:337–360]) and reinvestigate it carefully using asymptotics and simulation. Our work reveals that the test is subject to power and size distortions, which are mainly caused by dependence or convergence rate changes under the null and alternative hypothesis. A dependent wild bootstrap is newly suggested as a feasible remedy to such distortions. Our result provides a complete explanation as well as a solution to the problem that experienced by Aït-Sahalia [Testing continuous-time models of the spot interest rate. Rev Financ Stud. 1996;9:385–426], that is, that the test rejects true models too often when independent and identically distributed asymptotic critical values are used.     

Semiparametric methods in nonlinear time series analysis: a selective review

Time series analysis is a tremendous research area in statistics and econometrics. In a previous review, the author was able to break down up 15 key areas of research interest in time series analysis. Nonetheless, the aim of the review in this current paper is not to cover a wide range of somewhat unrelated topics on the subject, but the key strategy of the review in this paper is to begin with a core the ‘curse of dimensionality’ in nonparametric time series analysis, and explore further in a metaphorical domino-effect fashion into other closely related areas in semiparametric methods in nonlinear time series analysis.     

Nonparametric Bayesian analysis for multi-site hidden Markov model

The hidden Markov model (HMM) provides an attractive framework for modeling long-term persistence in a variety of applications including pattern recognition. Unlike typical mixture models, hidden Markov states can represent the heterogeneity in data and it can be extended to a multivariate case using a hierarchical Bayesian approach. This article provides a nonparametric Bayesian modeling approach to the multi-site HMM by considering stick-breaking priors for each row of an infinite state transition matrix. This extension has many advantages over a parametric HMM. For example, it can provide more flexible information for identifying the structure of the HMM than parametric HMM analysis, such as the number of states in HMM. We exploit a simulation example and a real dataset to evaluate the proposed approach.     

Predictive Modeling and Categorizing Likelihoods of Quarantine Pest Introduction of Imported Propagative Commodities from Different Countries

The present study investigates U.S. Department of Agriculture inspection records in the Agricultural Quarantine Activity System database to estimate the probability of quarantine pests on propagative plant materials imported from various countries of origin and to develop a methodology ranking the risk of country–commodity combinations based on quarantine pest interceptions. Data collected from October 2014 to January 2016 were used for developing predictive models and validation study. A generalized linear model with Bayesian inference and a generalized linear mixed effects model were used to compare the interception rates of quarantine pests on different country–commodity combinations. Prediction ability of generalized linear mixed effects models was greater than that of generalized linear models. The estimated pest interception probability and confidence interval for each country–commodity combination was categorized into one of four compliance levels: “High,” “Medium,” “Low,” and “Poor/Unacceptable,” Using K‐means clustering analysis. This study presents risk‐based categorization for each country–commodity combination based on the probability of quarantine pest interceptions and the uncertainty in that assessment.     

Recent developments in high dimensional covariance estimation and its related issues,a review

In this paper we review some of recent developments in high dimensional data analysis, especially in the estimation of covariance and precision matrix, asymptotic results on the eigenstructure in the principal components analysis, and some relevant issues such as test on the equality of two covariance matrices, determination of the number of principal components, and detection of hubs in a complex network.