The Quality of Life in Korea: Comparative and Dynamic Perspectives

Social Indicators Research -     

Partially Collapsed Gibbs Sampling for Linear Mixed-effects Models

This article presents a novel Bayesian analysis for linear mixed-effects models. The analysis is based on the method of partial collapsing that allows some components to be partially collapsed out of a model. The resulting partially collapsed Gibbs (PCG) sampler constructed to fit linear mixed-effects models is expected to exhibit much better convergence properties than the corresponding Gibbs sampler. In order to construct the PCG sampler without complicating component updates, we consider the reparameterization of model components by expressing a between-group variance in terms of a within-group variance in a linear mixed-effects model. The proposed method of partial collapsing with reparameterization is applied to the Merton’s jump diffusion model as well as general linear mixed-effects models with proper prior distributions and illustrated using simulated data and longitudinal data on sleep deprivation.     

Performance analysis of re-entrant flow shop with single-job and batch machines using mean value analysis

We propose an approximate method based on the mean value analysis for estimating the average performance of re-entrant flow shop with single-job machines and batch machines. The main focus is on the steady-state averages of the cycle time and the throughput of the system. Characteristics of the re-entrant flow and inclusion of the batch machines complicate the exact analysis of the system. Thus, we propose an approximate analytic method for obtaining the mean waiting time at each buffer of the workstation and a heuristic method to improve the result of the analytic method. We compare the results of the proposed approach with a simulation study using some numerical examples.     

New employee orientation: cases of Korean corporations

Despite its effectiveness in socialization and development, new employee orientation (NEO) as a stand-alone training intervention has rarely been a topic of interest in the academic world. The purpose of this study was to examine the NEO programmes for university graduates in Korean corporations. Through an extensive review of NEO-related materials in 10 large Korean corporations, the designs and contents of Korean NEOs were analysed. As a result, all investigated corporations were found to use most of the institutionalized socialization tactics: formal, collective, fixed, sequential, and serial. The contents of the NEOs mainly focused on the synergism and integration roles. The embedded national culture and organizational contexts in Korean corporations were explored to explain the practices of the NEOs. Implications for HRD practice and research were suggested.     

Inventory Sharing in the Presence of Commodity Markets

This study investigates the value of inventory sharing in the presence of spot and forward markets. We consider a multi‐period setting where two firms process a common commodity to meet stochastic demands. They can buy and sell the commodity through both the spot and forward markets. They can also share the commodity if one has leftover inventory while the other has excess demand. We first characterize the equilibrium strategies of the two firms. Our analysis reveals that in such a context, the value of inventory sharing is low when the forward price is directly used to value the sharing transactions. We then develop a structured trans‐shipment price scheme that uses a linear combination of the spot and forward prices. We show that this method can substantially increase the value of inventory sharing. Our analysis also reveals that in the presence of liquid spot and forward markets, the value of inventory sharing mainly results from the difference of the transaction costs, and it increases if the market in which firms operate becomes more competitive.     

Understanding how health journalists judge public relations sources: A rules theory approach

The research presented here offers public relations practitioners and scholars insight about how health journalists (N = 598) view practitioners and evaluate the appropriateness of public relations materials by public relations source (e.g., nonprofit, government). Also assessed are differences in journalist perceptions according to medium (e.g., newspapers, magazines) and market (e.g., national, metropolitan). Rules theory guides the analysis, allowing practitioners to discern journalists’ general and specific rules for accepting publicity materials. Findings show that health journalists are least accepting of material from businesses and federal government agencies. Newspaper and freelance health journalists are more reluctant to use public relations materials than are other journalists.     

Model-Averaged Benchmark Concentration Estimates for Continuous Response Data Arising from Epidemiological Studies

Worker populations often provide data on adverse responses associated with exposure to potential hazards. The relationship between hazard exposure levels and adverse response can be modeled and then inverted to estimate the exposure associated with some specified response level. One concern is that this endpoint may be sensitive to the concentration metric and other variables included in the model. Further, it may be that the models yielding different risk endpoints are all providing relatively similar fits. We focus on evaluating the impact of exposure on a continuous response by constructing a model-averaged benchmark concentration from a weighted average of model-specific benchmark concentrations. A method for combining the estimates based on different models is applied to lung function in a cohort of miners exposed to coal dust. In this analysis, we see that a small number of the thousands of models considered survive a filtering criterion for use in averaging. Even after filtering, the models considered yield benchmark concentrations that differ by a factor of 2 to 9 depending on the concentration metric and covariates. The model-average BMC captures this uncertainty, and provides a useful strategy for addressing model uncertainty.     

A balanced multi-level rotation sampling design and its efficient composite estimators

We present a multi-level rotation sampling design which includes most of the existing rotation designs as special cases. When an estimator is defined under this sampling design, its variance and bias remain the same over survey months, but it is not so under other existing rotation designs. Using the properties of this multi-level rotation design, we derive the mean squared error (MSE) of the generalized composite estimator (GCE), incorporating the two types of correlations arising from rotating sample units. We show that the MSEs of other existing composite estimators currently used can be expressed as special cases of the GCE. Furthermore, since the coefficients of the GCE are unknown and difficult to determine, we present the minimum risk window estimator (MRWE) as an alternative estimator. This MRWE has the smallest MSE under this rotation design and yet, it is easy to calculate. The MRWE is unbiased for monthly and yearly changes and preserves the internal consistency in total. Our numerical study shows that the MRWE is as efficient as GCE and more efficient than the existing composite estimators and does not suffer from the drift problem [Fuller W.A., Rao J.N.K., 2001. A regression composite estimator with application to the Canadian Labour Force Survey. Surv. Methodol. 27 (2001) 45–51] unlike the regression composite estimators.     

Rates and correlates of recurrent psychiatric crisis episodes among children and adolescents in state custody

The purpose of this study was to determine the extent of and factors associated with recurrent psychiatric crisis episodes among children and adolescents in state custody. A total of 1362 children ages 3 to 16 years who were in custody of the child welfare agency and underwent a psychiatric crisis screening and services for the first time between 2001 and 2003 were followed for the same observation period of 24 months. Logistic regression was used to determine the clinical and non-clinical factors associated with a return to psychiatric crisis screening and services. Overall, 44.6% of the sample had another psychiatric crisis episode in the following two years. Nearly two thirds of those who returned did so within 6 months of their first crisis episode. A greater likelihood of recidivism was associated with severity of psychiatric illness, being female, white, in residential care placement, and having placement instability. Recurrent psychiatric crises appear to be predictable using readily available variables, which can inform interventions designed to reduce repeat episodes.     

Validation and Psychometric Properties of Academic Major Satisfaction Scale Among Korean College Students

The purpose of this research was to adapt and validate the 6-items Academic Major Satisfaction Scale (AMSS, Nauta in J Career Assess 15(4):446–462, 2007) for use in Korea. The scale was tested using 275 college students in South Korea. Results indicated adequate internal-consistency reliability of 0.87, and adequate test–retest reliability of 0.84. Confirmatory factor analysis demonstrated a unidimensional structure and measure invariance tests showed equivalent structure across gender groups. Correlations with career decision self-efficacy and variables related to subjective well-being ranged from moderate-tohigh and were all significant. All the results suggest suitable fit among the population of Korean college students. Suggestions for usage of and future research on the AMSS in the Korean context are discussed.