VIF-based adaptive matrix perturbation method for heteroskedasticity-robust covariance estimators in the presence of multicollinearity

In this study, we investigate linear regression having both heteroskedasticity and collinearity problems. We discuss the properties related to the perturbation method. Important observations are summarized as theorems. We then prove the main result that states the heteroskedasticity-robust variances can be improved and that the resulting bias is minimized by using the matrix perturbation method. We analyze a practical example for validation of the method.     

Child Benefit Portfolios Across OECD Countries

Current research on the cross-national pattern of investment in child benefits mostly adopts the total resources approach and the model family method. The total resources approach conducts a broad comparison of the aggregate expenditure of different types of child benefit across countries. The model family method adds sophistication by comparing the values of child benefit packages of different countries, which combines different levels of spending in each type of child benefit, based on different family types with certain assumed characteristics. To complement the existing approaches, this study uses cluster analysis to classify countries into groups of similar investment strategies by simultaneously counting the different types and levels of child benefits of all countries. The findings show that four types of child benefit investment portfolio, namely Active, Moderate, Conservative, and Minimal, can be identified across OECD countries. While some studies have focused on the effects of individual types of child benefit on child outcomes, little is known about the effects of child benefits as a whole. The pattern of child benefits as investment portfolios could serve as a basis facilitating further investigation into its relationship with child outcomes. Preliminary findings indicate that child poverty, health, and satisfaction with school life differ significantly across investment portfolios, especially Active Investment outperforms Minimal Investment consistently.     

A reference activity model for smart factory design and improvement

Smart manufacturing systems (SMSs) are envisioned to contain highly automated and IT-driven production systems. To address the complexity that arises in such systems, a standard and holistic model for describing its activities and their interrelationships is needed. This paper introduces a factory design and improvement (FDI) activity model and illustrates a case study of FDI in an electromechanical component factory. In essence, FDI is a reference activity model that encompasses a range of manufacturing system activities for designing and improving a factory during its initial development and also its operational phases. The FDI model shows not only the dependency between activities and manufacturing control levels but also the pieces of information and software functions each activity relies on. We envision that the availability of these pieces of information in digital form to integrate across the software functions will increase the agility of factory design and improvement projects. Therefore, our future work lies in contributing to standards for exchanging such information.     

Stationarity test of electromyographic signals during isokinetic trunk exertions

The aim of this study is to investigate the stationarity of the electromyographic (EMG) signals during isokinetic exertions of the trunk muscle. Six healthy subjects participated in this study. The erector spinae muscles were used to collect the signals. In order to simulate the isokinetic exercises of the trunk, a Cybex system with a trunk modular component was used. All subjects performed sustained exertions with a combination of load (25%, 50% MVC) and angular velocity (0, 15, 30 degree/s). The stationarity of the signals was tested by the reverse arrangements test and modified reverse arrangements test. In the results, the signal stationarity was high in all conditions in the reverse arrangements test. However, in the modified reverse arrangements test it was relatively low at about the 30 degree/s angular velocity. In the analysis of variance, the effect of angular velocity was statistically significant at the 0.05 significance level in the modified reverse arrangements test and Tukey's HSD grouping showed that the stationarity of 30 degree/s angular velocity was significantly different from 0, 15 degree/s condition. These results indicate that the stationarity of the EMG signals showed no difference between isometric and isokinetic conditions when the angular velocity was equal to 15 degree/s.     

A Social Network Contagion Theory of Risk Perception

Risk perceptions have, to a great extent, been studied exclusively as individual cognitive mechanisms in which individuals collect, process, and form perceptions as atomized units unconnected to a social system. These individual-level theories do not, however, help explain how perception of risk may vary between communities or within a single community. One alternative approach is based on a network theory of contagion. This approach, emerging largely from organizational and community social network studies, suggests that it is the relational aspects of individuals and the resulting networks and self-organizing systems that influence individual perceptions and build "groups or communities of like-minded" individuals. These social units, it is argued, behave as attitude, knowledge, or behavioral structures. The study reported in this article tests one aspect of this theoretical perspective. The central hypothesis proposes the existence of risk perception networks--relational groupings of individuals who share, and perhaps create, similar risk perceptions. To test this idea, data were collected from individuals involved in a community environmental conflict over a hazardous waste site cleanup. The statistical analysis used a matrix of relational social linkages to compare with a matrix of individual risk perceptions The analysis confirmed the hypothesis suggesting that social linkages in communities may play an important role in focusing risk perceptions.     

Basic Psychological Need Profiles and Correlates in Volunteers for a National Sports Event

VOLUNTAS: International Journal of Voluntary and Nonprofit Organizations - According to the basic psychological need theory, satisfaction and frustration of basic psychological needs are related to...     

The psychosocial needs of the Chinese elderly

Changing Chinese family patterns caused by immigration have contributed to the breakdown of traditional community and familial control in Chinese-American families. As a result, the Chinese-American elderly are faced with unique psychosocial problems that workers must consider when providing services to this population.     

How Samsung organized for innovation

This study examines a Korean firm, the Samsung Corporation, to find out: What are the characteristics of the organizational innovations in the era of globalization? What are the consequences of the organizational innovations? What problems does the company face in implementing them? And what are the remedies to overcome those problems? The company has made efforts in three ways: 1. operating teams; 2. flattening of hierarchy; and 3. networking. These three innovations were interrelated and can be often observed in a single organization which is labelled a “Clustered Web” organization. The innovations faced problems and required time to be implemented. Remedies for those problems and implications are discussed.     

A Weighting Approach for GEE Analysis with Missing Data

We propose a new weighting (WT) method to handle missing categorical outcomes in longitudinal data analysis using generalized estimating equations (GEE). The proposed WT provides a valid GEE estimator when the data are missing at random (MAR), and has more stable weights and shows advantage in efficiency compared to the inverse probability weighing method in the presence of small observation probabilities. The WT estimator is similar to the stabilized weighting (SWT) estimator under mild conditions, but it is more stable and efficient than SWT when the associations of the outcome with the observation probabilities and the covariate are strong.