The relationship between wellness participation and health care benefit utilization

To examine the relationship between participation in a wellness program and the amount of absenteeism and medical claims, seven years of retrospective absenteeism and medical claims records were collected for 207 employees (pre- and postwellness intervention) and entered into a database. A proportional stratified random sample of workers by wellness participation was selected. While there was no significant change in the amount of sick leave taken over time, a log transformation revealed a significant increase in the dollar amount of medical claims over time, particularly for the middle-aged group of employees. This confirms that wellness intervention slowed the rate of increasing claims among middle-aged participants after just three years of wellness intervention.     

Pitfalls and opportunities for environmental marketers

Issues such as global warming, ozone depletion, insufficient landfill capacity, and excess packaging are foremost on the minds of consumers. Companies face a myriad of environmental challenges, but they also recognize the opportunities to be gained by implementing responsible marketing action plans.     

Guidelines for services and amenities in developing communities∗

Urban development in Southern Africa has reflected western values and standards relating to health, safety, order, amenity, convenience and general welfare, and only incidentally to efficiency and economy. This article describes a project which relates to different value systems, and has different objectives. It highlights the imperatives for change, namely population growth, urbanisation and declining per capita GDP growth. In this milieu, the objective of affordability becomes paramount Standards are related to resources and are based on consultation with the developing community.

The article describes four key elements in the ‘Guidelines for Services and amenities’ being prepared by the CSIR for the Department of Development Aid, namely stormwater management, public transport, road layout and development density. It concludes by cautioning against development policies which deny or misunderstand the economic forces which drive the process of urbanisation.     

On the variance of the ratio estimator

Summary In an earlier paper [Rao 1966] an exact expression for the variance of the ratio estimator under theMidzuno-Sen sampling scheme is obtained and here we study some of the interesting properties of the coefficients involved in this expression which depend on the auxiliary information. Use of these coefficients is made of in finding out an exact expression for the Bias and Mean Square Error of the ratio estimator under Simple Random Sampling With-Out Replacement (SRSWOR) scheme.     

Robustness issues in multilevel regression analysis

A multilevel problem concerns a population with a hierarchical structure. A sample from such a population can be described as a multistage sample. First, a sample of higher level units is drawn (e.g. schools or organizations), and next a sample of the sub‐units from the available units (e.g. pupils in schools or employees in organizations). In such samples, the individual observations are in general not completely independent. Multilevel analysis software accounts for this dependence and in recent years these programs have been widely accepted. Two problems that occur in the practice of multilevel modeling will be discussed. The first problem is the choice of the sample sizes at the different levels. What are sufficient sample sizes for accurate estimation? The second problem is the normality assumption of the level‐2 error distribution. When one wants to conduct tests of significance, the errors need to be normally distributed. What happens when this is not the case? In this paper, simulation studies are used to answer both questions. With respect to the first question, the results show that a small sample size at level two (meaning a sample of 50 or less) leads to biased estimates of the second‐level standard errors. The answer to the second question is that only the standard errors for the random effects at the second level are highly inaccurate if the distributional assumptions concerning the level‐2 errors are not fulfilled. Robust standard errors turn out to be more reliable than the asymptotic standard errors based on maximum likelihood.     

An Average Derivative Estimation of Stochastic Frontiers

This paper utilizes the average derivative estimation of Stoker (1986) and the pesudo-likelihood estimation of Fan, Li, and Weersink (1996) to estimate a semiparametric stochastic frontier regression, y = g(x) + , where the function g(.)is unknown and is a composite error in a standard setting. The proposed semiparametric method of estimation is applied to data on farmers' credit unions in Taiwan. Empirical results show that the banking services of the farmers' credit unions is subject to economies of scale, but high degree of cost inefficiency in operation.