Assessing and Improving the Performance of Nearly Efficient Unit Root Tests in Small Samples

Abstract

The development of unit root tests continues unabated, with many recent contributions using techniques such as generalized least squares (GLS) detrending and recursive detrending to improve the power of the test. In this article, the relation between the seemingly disparate tests is demonstrated by algebraically nesting all of them as ratios of quadratic forms in normal variables. By doing so, and using the exact sampling distribution of the ratio, it is straightforward to compute, examine, and compare the test' critical values and power functions. It is shown that use of GLS detrending parameters other than those recommended in the literature can lead to substantial power improvements. The open and important question regarding the nature of the first observation is addressed. Tests with high power are proposed irrespective of the distribution of the initial observation, which should be of great use in practical applications.     

Structural holes and managerial performance: Identifying the underlying mechanisms

Structural holes theory suggests a variety of possible explanations for the empirically observed relationship between structural holes and individual managerial performance. However, little has been done to disentangle one mechanism from another. This paper empirically tests a mediated moderation model that distinguishes between the five different theoretical mechanisms: autonomy, competition, information brokering, opportunity recognition and innovativeness. The findings suggest that of these five theoretical causal motors, innovativeness plays a key role in linking network structure and network content to performance.     

Examining the structure of awareness and perceptions of groundnut aflatoxin among Ghanaian health and agricultural professionals and its influence on their actions

This study uses a modified health belief model (HBM) within a socio-economic framework to evaluate the influence of awareness and knowledge on actions to reduce aflatoxin (AF) contamination in groundnuts (peanuts). Data were collected in 2002 through a self-administered questionnaire from a sample of 367 individuals. Socio-economic factors affecting perceptions, awareness, knowledge, and action were examined using structural equation modeling. The perceived benefits of good quality groundnuts and/or groundnut products were the most important determinants of awareness and knowledge of AF among agricultural and health professionals in Ghana. Awareness, in turn, had a significant causal effect on the professionals’ decisions to take actions to increase the level of awareness of AF in the society. Demographic factors, such as gender and level of education significantly influenced knowledge of AF and the perception of the benefits of good quality groundnut. Type of profession had a significant influence on awareness and perceived seriousness of the AF problem. Education was a significant determinant of awareness of AF in groundnuts. The study generates important information for policy decision making when considering resource allocation to reduce food contamination in developing economies.     

Social Harmony in Hong Kong: Level,Determinants and Policy Implications

This study aims at ascertaining how Hong Kong people perceive Hong Kong as a harmonious society. It also identifies the elements that are most conducive to social harmony in Hong Kong, so that the government could take reference when formulating new policies. 1,062 adults residents were asked to rate their perceived level of social harmony and their satisfaction with 36 items (divided into three dimensions: public governance, society, and economy, family and work) for which the research team believes would be influencing the perceived level of social harmony. Results show that the average rating of social harmony was 5.57 (out of 10), delineating a moderate level of social harmony. Subsequent multivariate factor analysis and regression analysis show that the four extracted factors (from the three dimensions) had significant impacts on the level of social harmony. These were, in order of significance: (a) public governance, (b) social solidarity and respect, (c) economy/family/work and, (d) social tolerance and progressiveness. According to the factor loadings of each significant factor, we identified four core values which we hope the government would consider when formulating new policies, as follows: (1) A Justice Government with Sincerity on Communication, (2) Mutual Support and Respect with Integrity and Dedication, (3) Dedication to One’s Job and Community by Helping the Needed and, (4) Creativity and Progressiveness with Tolerance. Implications for policy making are discussed. The study was conducted under the direction and guidance of the Fostering Social Harmony Task Force of the Hong Kong Professionals and Senior Executives Association (HKPASEA). The authors acknowledge the kind support and assistance provided by the Council Members of HKPASEA and staff members of the Centre for Corporate Governance and Financial Policy at Hong Kong Baptist University. We are also grateful to Prof. Alex Michalos and Prof. P. K. Ip for their comments and suggestions given at the International Conference on National Well-Being held in November 2006 at the National Central University, Taiwan.     

Suicide ideation among US college students. Associations with other injury risk behaviors

Suicide, the endpoint of a continuum that begins with suicide ideation, is the third leading cause of death among the US college-aged population. The first and second leading causes of death among this age group, unintentional injury and homicide, may also be linked to suicide ideation. We used data from the National College Health Risk Behavior Survey to examine the association between suicide ideation and injury-related behaviors among 18- to 24-year-old college students. Students who reported suicide ideation were significantly more likely than students who did not report considering suicide to carry a weapon, engage in a physical fight, boat or swim after drinking alcohol, ride with a driver who had been drinking alcohol, drive after drinking alcohol, and rarely or never used seat belts. Given this clustering of injury-related risk behaviors, college prevention programs should aim to reduce risks for injuries comprehensively, rather than addressing each risk behavior separately.     

A comparative assessment of public opinion toward immigrants and immigration policies

"This article is part of a larger study of public attitudes toward immigration in seven countries that historically and currently have had different policies and practices vis-a-vis immigration. The countries involved are Australia, Canada, France, Germany, Great Britain, Japan and the United States. The time frame for which most of the public opinion data will be reported is from 1970 through 1995. The data have been collected from national surveys that were conducted in each of the countries."     

Revisiting the relationships among gender,marital status,and mental health

Three decades ago, Grove introduced his sex-role theory of mental illness, which attributes women's higher rates of psychological distress to their roles in society. Central to his hypothesis is that marriage is emotionally advantageous for men and disadvantageous for women. This article revisits this topic with data from the National Survey of Families and Households. The analyses indicate that the emotional benefits of marriage apply equally to men and women, but that men and women respond to marital transitions with different types of emotional problems. The implications of these findings for future research on gender and mental health are discussed.     

Attitudinal acceptance of intimate partner violence among U.S. adults

Attitudinal acceptance of intimate partner violence (IPV) is an important correlate of violent behavior. This study examined acceptance of IPV using data collected from a nationally representative telephone survey of 5,238 adults. Multivariable logistic regression analyses were used to test for associations between sociodemographic characteristics, exposure to violence, question order, and acceptance of hitting a spouse or boyfriend/girlfriend under specific circumstances. Depending on the circumstance examined, acceptance of IPV was significantly higher among participants who were male and younger than 35; were non-White; were divorced, separated, or had never married; had not completed high school; had a low household income; or were victims of violence within the past 12 months. Participants were more accepting of women hitting men; they also were consistently more likely to report tolerance of IPV if they were asked first about women hitting men rather than men hitting women. Reports of IPV tolerance need to be interpreted within the context of the survey. Efforts to change IPV attitudes can be tailored to specific IPV circumstances and subgroups, and these efforts should emphasize that the use of physical violence is unacceptable to both genders.     

The impact of an industry-based rehabilitation programme

An industry specific rehabilitation programme was developed to cater for the special requirements of the New Zealand logging industry. The aims of the rehabilitation programme were to: reduce the amount of time lost due to injury, reduce the number of lost time injuries, and overall, to reduce the direct costs associated with logging injuries. The programme was field-tested on a logging company. The rehabilitation programme was effective for reducing the average amount of time lost due to injury and also for reducing the cost of the injuries. Although there were a number of factors that may have had an impact upon these results, this research provides evidence that this rehabilitation programme was effective for reducing the severity and cost of injury to the New Zealand logging industry.