New approximate confidence intervals for the difference between two Poisson means and comparison

The problem of estimating the difference between two Poisson means is considered. A new moment confidence interval (CI), and a fiducial CI for the difference between the means are proposed. The moment CI is simple to compute, and it specializes to the classical Wald CI when the sample sizes are equal. Numerical studies indicate that the moment CI offers improvement over the Wald CI when the sample sizes are different. Exact properties of the CIs based on the moment, fiducial and hybrid methods are evaluated numerically. Our numerical study indicates that the hybrid and fiducial CIs are in general comparable, and the moment CI seems to be the best when the expected total counts from both distributions are two or more. The interval estimation procedures are illustrated using two examples.     

Inference for functions of parameters in discrete distributions based on fiducial approach: Binomial and Poisson cases

In this article, we propose a simple method of constructing confidence intervals for a function of binomial success probabilities and for a function of Poisson means. The method involves finding an approximate fiducial quantity (FQ) for the parameters of interest. A FQ for a function of several parameters can be obtained by substitution. For the binomial case, the fiducial approach is illustrated for constructing confidence intervals for the relative risk and the ratio of odds. Fiducial inferential procedures are also provided for estimating functions of several Poisson parameters. In particular, fiducial inferential approach is illustrated for interval estimating the ratio of two Poisson means and for a weighted sum of several Poisson means. Simple approximations to the distributions of the FQs are also given for some problems. The merits of the procedures are evaluated by comparing them with those of existing asymptotic methods with respect to coverage probabilities, and in some cases, expected widths. Comparison studies indicate that the fiducial confidence intervals are very satisfactory, and they are comparable or better than some available asymptotic methods. The fiducial method is easy to use and is applicable to find confidence intervals for many commonly used summary indices. Some examples are used to illustrate and compare the results of fiducial approach with those of other available asymptotic methods.     

Social Welfare System

The social welfare system in Korea has become a public issue recently. Before the 1997 financial crisis, policy makers as well as the general public were mainly interested in pursuing economic growth and largely downplaying welfare needs. In the wake of the crisis, however, the demand for welfare increased significantly, and this in turn has brought changes in the welfare structure, along with an expansion in welfare expenditures. This paper highlights the features of the Korean welfare system in terms of social insurance, pubic assistance, and social service. It examines the basic limitations and key issues surrounding the system. It compares the size of social welfare expenditures in Korea to other Organization for Economic Cooperation and Development (hereinafter the OECD) countries. In sum, welfare coverage, expenditures, and benefit levels are among the barriers to surmount especially in these times of high aspirations toward national unification and globalization.

     

RACIAL INEQUALITY IN MEN'S EMPLOYMENT AND RETIREMENT EARNINGS

Data from the New Beneficiary Study for currently married men who began receiving social security benefits in 1980–1981 indicate that the racial earnings gap is greater in retirement than it was in employment. Racial differences in employment and pension earnings are specified by education and employment status. There is, however, a significant net racial effect in predicting social security earnings. Furthermore, education interacts with race in predicting asset earnings, which constitute the major source of racial inequality in retirement. This analysis highlights not only the enduring problem of poverty for African Americans and Latinos who are "working off the books,' without social security benefits, but also the possibility of a "glass ceiling' that limits access to assets for highly educated nonwhites.     

Quality of Life Among Government Employees

The main purpose of this study is to examine distinctive aspects of the quality of life (QOL) of Korean government employees utilizing in large part many features of the 1999 QOL survey of Korean government and private sector employees. To this end, responses of government and private sector employees regarding various dimensions of QOL are compared. This study finds that the QOL of government employees is significantly lower than that of private sector employees. The result of regression analysis of QOL dimensions shows that the level of satisfaction with one's work environment is the most influential determinant of the overall QOL of Korean government employees. Based on this finding, this study recommends that the government agencies consider improving their employees' work-related environment.