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.     

Acculturation,Ethnicity, and Air Pollution Perceptions

A globalizing world increases immigration between nations, raising the question of how acculturation (or its lack) of immigrants and their descendants to host societies affects risk perceptions. A survey of Paterson, New Jersey, residents tested acculturation's associations with attitudes to air pollution and its management, and knowledge of and self‐reported behaviors concerning air pollution. Linguistic and temporal proxy measures for acculturation were independent variables along with ethnicity, plus controls for gender, age, education, and income in multivariate analyses. About one‐fifth of contrasts between non‐Hispanic whites, non‐Hispanic blacks, English‐interviewed Hispanics, and Spanish‐interviewed Hispanics were statistically significant (Bonferroni‐corrected) and of medium or higher affect size, with most featuring the Spanish‐interviewed Hispanics. Knowledge variables featured the most significant differences. Specifically, Spanish‐interviewed Hispanics reported less concern, familiarity with pollution, recognition of high pollution, and vigorous outdoor activity, and greater belief that government overregulates pollution than English‐interviewed Hispanics (and than the other two groups on most of these variables too). English‐interviewed Hispanics did not differ from non‐Hispanic whites, but did on several variables from non‐Hispanic blacks. Temporal proxies of acculturation among the foreign‐born were far less significant, but concern and familiarity with air pollution increased with time spent in the United States, while belief in overregulation and a positive trend in New Jersey pollution increased with time in the nation of origin. Implications of these acculturation and ethnicity findings for risk perception/communication research and practice are discussed.     

Temporal Relationships Among Depressive Symptoms,Risky Behavior Engagement,Perceived Control,and Gender in a Sample of Adolescents

The goals of the study were to examine whether (a) risky behaviors precede depressive symptoms or, conversely, depressive symptoms predict risky behavior engagement; (b) gender moderates the relationship between risky behavior engagement and depressive symptoms; and (c) perceived control strengthens the association between risky behavior engagement and depressive symptoms. At Time 1, 118 adolescents completed self‐report measures assessing perceived control, risky behavior engagement, and depressive symptoms. Follow‐up assessments occurred every 6 weeks (Times 2–5), and participants completed measures assessing risky behavior engagement and depressive symptoms. Results indicated that neither risky behavior engagement nor depressive symptoms emerged as main effects for the sample as a whole. When examining the relationship between depressive symptoms and risky behavior engagement as a function of gender, boys', but not girls', risky behavior engagement predicted higher levels of depressive symptoms. Irrespective of whether we examined boys or girls, depressive symptoms did not predict risky behavior engagement. With regards to the role of cognitive vulnerability, adolescents with lower levels of perceived control reported higher levels of depressive symptoms following risky behavior engagement. These findings suggest that both gender and cognitive vulnerability factors may potentiate the relationship between risky behavior engagement and subsequent depressive symptoms.     

On concurrence of several linear regressions and applications to problems of enzyme kinetics

In comparing several regressions E(y_ij) =α_i + β_ix_ij i = 1, 2, ..., k, j = 1,2, ..., n_i, researchers are generally interested in the following five problems: whether they have (1) equal slope, (2) equal intercept, (3) coincidence, (4) common intersection on X-axis, and (5) common intersection on (X,Y) - plane. Problems (1) - (3) can be put into the framework of the general linear hypothesis and the F-test can be used. However, problems (4) and (5) cannot be put into the general linear hypothesis because they are ratios of parameters. Hence, in this paper we consider the generalized likelihood ratio test for hypothesis testing. An application to an enzyme kinetics problem in Aniline Metabolism is demonstrated     

Reliability and Validity of the World Health Organization Quality of Life: Brief Version (WHOQOL-BREF) in a Homeless Substance Dependent Veteran Population

With the high number of homeless, there is a critical need for rapid and accurate assessment of quality of life to assess program outcomes. The World Health Organization’s WHOQOL-100 has demonstrated promise in accurately assessing quality-of-life in this population. However, its length may make large scale use impractical for working with a homeless population. The World Health Organization Quality of Life—Brief version (WHOQOL-BREF), though providing a shorter instrument and being, theoretically, more manageable has not been evaluated for use with homeless individuals. This study evaluated the psychometric properties of the WHOQOL-BREF in 389 homeless veterans. Adequate internal consistency for all domains was found and validity for each domain was supported using the Personality Assessment Inventory. The WHOQOL-BREF provides a reliable, valid, and brief assessment of quality-of-life. Due to the length of the instrument and the domains covered, it could have great utility in the assessment of homeless populations with multiple problem domains.