Alternative tests for heteroscedasticity of disturbances:a comparative study

This paper presents three small sample tests for testing the heteroscedasticity among regression disturbances. The power of these tests are compared with two of the leading tests for this hypothesis, one by Goldfeld and Quandt [5] and the other by Theil [17]. We also provide a heuristic method of selecting the number of middle observations to be deleted for the Goldfeld-Quandt type of tests.     

Marginally oversaturated designs

A special class of supersaturated design, called marginally over saturated design (MOSD), in which the number of variables under investigation (k) is only slightly larger than the number of experimental runs (n), is presented. Several optimality criteria for supersaturated designs are discussed. It is shown that the resolution rank criterion is most appropriate for screening situations. The construction method builds on two major theorems which provide an efficient way to evaluate resolution rank. Examples are given for the cases n=8, 12, 16, and 20. Potential extensions for future work are discussed.     

Data skeletons: simultaneous estimation of multiple quantiles for massive streaming datasets with applications to density estimation

We consider the problem of density estimation when the data is in the form of a continuous stream with no fixed length. In this setting, implementations of the usual methods of density estimation such as kernel density estimation are problematic. We propose a method of density estimation for massive datasets that is based upon taking the derivative of a smooth curve that has been fit through a set of quantile estimates. To achieve this, a low-storage, single-pass, sequential method is proposed for simultaneous estimation of multiple quantiles for massive datasets that form the basis of this method of density estimation. For comparison, we also consider a sequential kernel density estimator. The proposed methods are shown through simulation study to perform well and to have several distinct advantages over existing methods.     

Learning from a lot: Empirical Bayes for high‐dimensional model‐based prediction

Empirical Bayes is a versatile approach to “learn from a lot” in two ways: first, from a large number of variables and, second, from a potentially large amount of prior information, for example, stored in public repositories. We review applications of a variety of empirical Bayes methods to several well‐known model‐based prediction methods, including penalized regression, linear discriminant analysis, and Bayesian models with sparse or dense priors. We discuss “formal” empirical Bayes methods that maximize the marginal likelihood but also more informal approaches based on other data summaries. We contrast empirical Bayes to cross‐validation and full Bayes and discuss hybrid approaches. To study the relation between the quality of an empirical Bayes estimator and p, the number of variables, we consider a simple empirical Bayes estimator in a linear model setting. We argue that empirical Bayes is particularly useful when the prior contains multiple parameters, which model a priori information on variables termed “co‐data”. In particular, we present two novel examples that allow for co‐data: first, a Bayesian spike‐and‐slab setting that facilitates inclusion of multiple co‐data sources and types and, second, a hybrid empirical Bayes–full Bayes ridge regression approach for estimation of the posterior predictive interval.     

Computer‐Mediated Communication in Intimate Relationships: Associations of Boundary Crossing,Intrusion, Relationship Satisfaction,and Partner Responsiveness

This study examined the impact of technology on couples in committed relationships through the lens of the couple and technology framework. Specifically, we used data from 6,756 European couples to examine associations between online boundary crossing, online intrusion, relationship satisfaction, and partner responsiveness. The results suggest that participants’ reports of online boundary crossing were linked with lower relationship satisfaction and partner responsiveness. Also, lower relationship satisfaction and partner responsiveness were associated with increased online boundary crossing. The results suggest that men, but not women, who reported greater acceptability for online boundary crossing were more likely to have partners who reported lower relationship satisfaction in their relationships. Implications for clinicians, relationship educators, and researchers are discussed.     

Some Cautions on the Measurement of User Information Satisfaction*

User information satisfaction (UIS) is important because of its potential effects on MIS department goals, quality of user work life, and extent of voluntary usage of systems. Reliable measurement of UIS is important for providing evaluative information for both researchers and practitioners. This study used 92 managers and executives as subjects to compare the test/retest reliability of a widely used, 13-scale UIS instrument together with four summary questions under experimental and control conditions. The summary questions behaved more reliably than the detailed questions for all groups, perhaps because of problems with scale units and origins and with item heterogeneity. This suggests that researchers need more reliable measures of UIS and that practitioners need to exercise caution when collecting and interpreting UIS scores.     

澳大利亚的矿产勘查

地质勘查具有高风险、高成本、周期长等特点,不可避免地与尽快实现找矿突破、为快速发展的经济社会提供支撑的迫切愿望存在矛盾。如何有效地加强矿产勘查,建立和完善合理的地质勘查新机制,尽可能降低矿产勘查的风险和投资成本,进而促进矿产勘查的重大突破?发达国家的政府在矿产勘查工作中采取了一系列有力的措施,积累了丰富经验。下面以澳大利亚为例,介绍一下他们的矿产勘查情况。     

The relationship between Black and gay community involvement and HIV-related risk behaviors among Black men who have sex with men

Black gay men must navigate identities and stigmas related to being gay and Black, and report higher HIV incidence relative to their White male counterparts although they report lower rates of drug use and risky sexual behaviors. This study examined whether closeness to the gay or Black community correlated with HIV-related risk and protective behaviors. Data were drawn from uConnect, a population-based cohort study of young Black men who have sex with men (YBMSM) on Chicago's South Side. The sample consists of 618 Black MSM ranging in age from 16 to 29. Cross-sectional measures for this study include Black and gay community closeness, drug use, sexual risk behaviors, HIV testing, and health promotion behaviors. Closeness with the gay community was associated with greater pre-exposure prophylaxis (PrEP) knowledge as well as participating in health promotion programs along with higher rates of transactional sex and having sex under the influence of substances, and increased odds of self-reported HIV seropositivity. Involvement in the Black community was associated with lower odds of reporting being HIV positive. Findings suggest that programs and initiatives are needed to help promote the positive aspects of the Black and gay communities, while minimizing the negative correlates of such involvements.     

“It’s a generosity loop”: Religious and spiritual motivations of volunteers who glean produce to reduce food insecurity

Food insecurity is a common social issue and households look to assistance from food pantries, which often have difficulty supplying fresh or nutritious food. A substantial amount of produce is left in the fields, which can be collected through gleaning. In a focus group with volunteer gleaners at a faith-based nonprofit organization that attempts to fill the gaps of food insecurity, the motivations, challenges, and benefits of volunteering were examined. Volunteering in gleaning generated a sense of collective purpose and community; it addressed deeply held religious and spiritual impulses; and it puts volunteers directly in contact with nature.