The numerical evaluation of the distribution function of a bilinear from to a quadratic from with econometric examples

This paper considers a general and computationally convenient method of evaluating the distribution function of statistics that are the ratio of a bilinear form to a quadratic form. Numerous Economemc applications of the method are given.     

An improved alternative estimation procedure for current population mean in presence of positively and negatively correlated auxiliary variables in two-occasion rotation patterns

Abstract

The present study confirms the influential role of a positively and a negatively correlated auxiliary variables in enhancing the precision of estimates of current population mean in two occasion rotation (successive) sampling. Exponential-type estimators of current population mean have been proposed for three different situations: (i) the information on a positively correlated auxiliary variable is readily available on both occasions (ii) the information on a negatively correlated auxiliary variable is readily available on both occasions and (iii) the information on both positively and negatively correlated auxiliary variables are readily available on both the occasions. The characteristics of the proposed estimators have been explored and their efficacious performances are compared with the natural and recent contemporary estimators. Optimum replacement strategies of the proposed estimation procedures have been formulated. Simulation and empirical studies are carried out to justify the proposition of the proposed estimators and appropriate recommendations have been put forward to the survey practitioners.     

Network Embeddedness in Exploration and Exploitation of Joint R&D Projects: A Structural Approach

This paper analyses how network embeddedness affects the exploration and exploitation of R&D project performance. By developing joint projects, partners and projects are linked to one another and form a network that generates social capital. We examine how the location, which determines the access to information and knowledge within a network of relationships, affects the performance of projects. We consider this question in the setup of exploration and exploitation projects, using a database built from an EU framework. We find that each of the structural embeddedness dimensions (degree, betweenness and eigenvector centrality) have a different impact on the exploration and exploitation project performance. Our empirical analysis extends to project management literature and social capital theory, by including the effect that the acquisition of external knowledge has on the performance of the project.     

A New Quantile Function with Applications to Reliability Analysis

In this article, we propose a new class of distributions defined by a quantile function, which nests several distributions as its members. The quantile function proposed here is the sum of the quantile functions of the generalized Pareto and Weibull distributions. Various distributional properties and reliability characteristics of the class are discussed. The estimation of the parameters of the model using L-moments is studied. Finally, we apply the model to a real life dataset.     

Validation of Nonparametric Two-sample Bootstrap in ROC Analysis on Large Datasets

The nonparametric two-sample bootstrap is applied to computing uncertainties of measures in receiver operating characteristic (ROC) analysis on large datasets in areas such as biometrics, speaker recognition, etc. when the analytical method cannot be used. Its validation was studied by computing the standard errors of the area under ROC curve using the well-established analytical Mann–Whitney statistic method and also using the bootstrap. The analytical result is unique. The bootstrap results are expressed as a probability distribution due to its stochastic nature. The comparisons were carried out using relative errors and hypothesis testing. These match very well. This validation provides a sound foundation for such computations.     

Methods to assess measurement error in questionnaires of sedentary behavior

Sedentary behavior has already been associated with mortality, cardiovascular disease, and cancer. Questionnaires are an affordable tool for measuring sedentary behavior in large epidemiological studies. Here, we introduce and evaluate two statistical methods for quantifying measurement error in questionnaires. Accurate estimates are needed for assessing questionnaire quality. The two methods would be applied to validation studies that measure a sedentary behavior by both questionnaire and accelerometer on multiple days. The first method fits a reduced model by assuming the accelerometer is without error, while the second method fits a more complete model that allows both measures to have error. Because accelerometers tend to be highly accurate, we show that ignoring the accelerometer's measurement error, can result in more accurate estimates of measurement error in some scenarios. In this article, we derive asymptotic approximations for the mean-squared error of the estimated parameters from both methods, evaluate their dependence on study design and behavior characteristics, and offer an R package so investigators can make an informed choice between the two methods. We demonstrate the difference between the two methods in a recent validation study comparing previous day recalls to an accelerometer-based ActivPal.     

Self-perception of Gambling Problems among Adolescents Identified as At-risk or Problem Gamblers

The relative influence of perceived familial addictive behaviors and personal gambling behaviors on adolescents' self-perceptions of gambling problems was examined. Students from five high schools in Connecticut (N = 3,886) were surveyed. Of those between the ages of 14 and 17 who scored two or more on the South Oaks Gambling Screen--Revised for Adolescents (n = 532; 72% male; 43% Caucasian), 14.3% reported having a current or past problem with gambling. Wagering larger amounts in a single day, gambling on a daily basis, and perceived presence of a family member with a gambling problem were associated with increased odds of self-perception of a gambling problem. Thus, adolescents who may be less likely to be identified for prevention efforts (due to lack of engagement in high stakes gambling or the real/perceived absence of a problematic gambler in the home) appear less likely to perceive a gambling problem. To advance prevention and treatment strategies, the apparent discrepancy between adolescents' self-perceptions and objective reports of problem gambling behaviors warrants further investigation.     

The effect of disability on the net worth of elderly people

As demographic shifts make the Social Security program financially vulnerable, the responsibility for income security in old age will shift from the government to elderly people. In this changing environment, the accumulation of wealth will be a crucial issue because wealth holders can draw income from assets, which can supplement retirement income. Thus, wealth (or net worth) is a proximate indicator of economic well-being of the elderly. This article presents the findings of a study of the net worth of elderly people with disabilities. The major findings were that a smaller proportion of elderly people with disabilities has assets of any type compared with elderly people with no disability; the dollar value of each type of asset is smaller among elderly people with disabilities than among elderly people with no disability; and the net worth of people with disabilities is smaller than that of elderly people with no disability even after other variables were controlled.