Statistical analysis of a two-unit dependent repairable system

Maximum likelihood estimators are investigated a for lr-out-of 2:G repairable system when failures and repairs are statistically dependent. Under two censoring schemes Accelerated Life Testing Procedure (ALTP) is used to obtain the estimates. Information matrices are supplied and a special case when the failure and repair phenomenon are independent of each other is considered.     

Residual Renyi entropy of k-record values

ABSTRACT

In this article, the residual Renyi entropy (RRE) of k-record values arising from an absolutely continuous distribution is considered. A representation of RRE of k-records arising from an arbitrary distribution in terms of RRE of k-record values arising from uniform distribution is given. Some properties for RRE of k-records are also discussed.     

Decision Making Clusters in Retirement Savings: Gender Differences Dominate

This study explored the impact of demographic factors on individuals’ investment choice decisions in retirement savings funds. Analysis found identifiable member clusters across a large and diverse sample of almost 150,000 transactions. Results suggested that gender and risk are the most dominant factors with women showing a strong tendency to make lower risk investment choices. If this behavioural tendency is not addressed through education it will accentuate the hurdles women already face in accumulating adequate saving for retirement.     

The Sources of Error in Psychology

The backgrounds and roles of school interpreters who provide interpretation services for limited English proficient students were investigated through a survey study. The results are based on a total of 89 interpreters working in schools throughout New York State. A total of 29 languages were represented in the two samples of interpreters with Spanish being the most frequently used language. Most of the interpreters had Bachelors Degrees or higher but very few had any formal training in interpretation. The results suggest that most interpreters work on a part-time basis. The interpreters reported providing services for a number of different school personnel while fulfilling numerous roles that included interpreting during assessment sessions as well as during parent meetings. The implications of the findings are discussed from the perspectives of the training and recruiting ofschool interpreters. The limitations of the findings are also examined.     

Robust methods of estimation of regression coefficients 1

Recently, cumulative residual entropy (CRE) has been found to be a new measure of information that parallels Shannon's entropy (see Rao et al. [Cumulative residual entropy: A new measure of information, IEEE Trans. Inform. Theory. 50(6) (2004), pp. 1220–1228] and Asadi and Zohrevand [On the dynamic cumulative residual entropy, J. Stat. Plann. Inference 137 (2007), pp. 1931–1941]). Motivated by this finding, in this paper, we introduce a generalized measure of it, namely cumulative residual Renyi's entropy, and study its properties. We also examine it in relation to some applied problems such as weighted and equilibrium models. Finally, we extend this measure into the bivariate set-up and prove certain characterizing relationships to identify different bivariate lifetime models.     

Reproductive and Developmental Risks from Ethylene Oxide: A Probabilistic Characterization of Possible Regulatory Thresholds

Ethylene oxide is a gas produced in large quantities in the United States that is used primarily as a chemical intermediate in the production of ethylene glycol, propylene glycol, non-ionic surfactants, ethanolamines, glycol ethers, and other chemicals. It has been well established that ethylene oxide can induce cancer, genetic, reproductive and developmental, and acute health effects in animals. The U.S. Environmental Protection Agency is currently developing both a cancer potency factor and a reference concentration (RfC) for ethylene oxide. This study used the rich database on the reproductive and developmental effects of ethylene oxide to develop a probabilistic characterization of possible regulatory thresholds for ethylene oxide. This analysis was based on the standard regulatory approach for noncancer risk assessment, but involved several innovative elements, such as: (1) the use of advanced statistical methods to account for correlations in developmental outcomes among littermates and allow for simultaneous control of covariates (such as litter size); (2) the application of a probabilistic approach for characterizing the uncertainty in extrapolating the animal results to humans; and (3) the use of a quantitative approach to account for the variation in heterogeneity among the human population. This article presents several classes of results, including: (1) probabilistic characterizations of ED10s for two quantal reproductive outcomes-resorption and fetal death, (2) probabilistic characterizations of one developmental outcome-the dose expected to yield a 5% reduction in fetal (or pup) weight, (3) estimates of the RfCs that would result from using these values in the standard regulatory approach for noncancer risk assessment, and (4) a probabilistic characterization of the level of ethylene oxide exposure that would be expected to yield a 1/1,000 increase in the risk of reproductive or developmental outcomes in exposed human populations.     

Financial capability and psychological health

Financial capability is receiving increasing interest among policy makers, who wish to reduce problem debt and welfare dependency and increase savings and general skills. We examine whether financial capability has impacts on psychological health independent of income and financial resources more generally using a nationally representative survey. Data from the British Household Panel Survey 1991-2006 are used to construct a measure of financial capability, which we relate to respondents’ psychological health using the 12-item General Health Questionnaire. Estimates from within-group panel data models indicate that financial capability has significant and substantial effects on psychological health over and above those associated with income and material wellbeing more generally. For men, having low financial capability has an effect larger than that associated with being unemployed, while for women it is similar to that of being divorced. Furthermore having low financial capability exacerbates the psychological costs associated with unemployment and divorce, while high financial capability reduces these costs.