VARIABLE SELECTION IN NONPARAMETRIC ADDITIVE MODELS

We consider a nonparametric additive model of a conditional mean function in which the number of variables and additive components may be larger than the sample size but the number of nonzero additive components is "small" relative to the sample size. The statistical problem is to determine which additive components are nonzero. The additive components are approximated by truncated series expansions with B-spline bases. With this approximation, the problem of component selection becomes that of selecting the groups of coefficients in the expansion. We apply the adaptive group Lasso to select nonzero components, using the group Lasso to obtain an initial estimator and reduce the dimension of the problem. We give conditions under which the group Lasso selects a model whose number of components is comparable with the underlying model, and the adaptive group Lasso selects the nonzero components correctly with probability approaching one as the sample size increases and achieves the optimal rate of convergence. The results of Monte Carlo experiments show that the adaptive group Lasso procedure works well with samples of moderate size. A data example is used to illustrate the application of the proposed method.     

‘Roots and wings’: an exploration of intergenerational play

Play is an important part of life, not only during childhood but also into adulthood and later life. While scholars have emphasized the physical, social, psychological, and cognitive benefits of play for children, few researchers have explored the role of play in later life. One context in which aging adults find opportunities to play is with their grandchildren. This qualitative study employed visual and text analyses to explore the experience of intergenerational play from the perspectives of grandchildren and grandparents. Findings indicated that both groups of participants were motivated to engage in play together, negotiated constraints to experience play, and received various benefits from playing with their grandparent or grandchild. Recommendations are provided to assist professionals in programming for intergenerational play and for further exploration of the motivations, benefits, and constraints associated with intergenerational play.     

Controlling type I error in the reference‐scaled bioequivalence evaluation of highly variable drugs

Reference‐scaled average bioequivalence (RSABE) approaches for highly variable drugs are based on linearly scaling the bioequivalence limits according to the reference formulation within‐subject variability. RSABE methods have type I error control problems around the value where the limits change from constant to scaled. In all these methods, the probability of type I error has only one absolute maximum at this switching variability value. This allows adjusting the significance level to obtain statistically correct procedures (that is, those in which the probability of type I error remains below the nominal significance level), at the expense of some potential power loss. In this paper, we explore adjustments to the EMA and FDA regulatory RSABE approaches, and to a possible improvement of the original EMA method, designated as HoweEMA. The resulting adjusted methods are completely correct with respect to type I error probability. The power loss is generally small and tends to become irrelevant for moderately large (affordable in real studies) sample sizes.     

Counselor happiness: Effects of therapy work with similar trauma

ABSTRACT

Many studies have researched burnout, compassion fatigue, secondary trauma, vicarious trauma, and shared trauma of practicing mental health professionals. Few have focused directly on the impact of personal trauma history on mental health professionals’ happiness. This exploratory study used an online survey to investigate the relationships among mental health professionals’ personal trauma history, happiness, and the effects of seeing clients with similar trauma. Personal trauma history was determined through a demographic survey and Posttraumatic Stress Disorder Checklist, and happiness was analyzed using the Oxford Happiness Questionnaire. The study examined several demographic variables to predict happiness. The study found that posttraumatic stress and number of client sessions were the most significant predictors of happiness.     

A New Dataset on Horizontal Structural Ethnic Inequalities in Thailand in Order to Address Sustainable Development Goal 10

The study accounts for the presence of endogeneity in the interdependence between social and institutional trust. Using Greece as a case study we provide valuable insights regarding the bidirectional nature of this relationship and its sign. Consequently, more accurate results might be provided regarding the determinants of both types of trust and the way in which these may be discerned in a given society. We use microdata extracted from the European Values Surveys (2002–2010) and instrumental variables techniques. Social trust is constructed as a three-item scale variable comprising generalized trust, fairness and helpfulness. The institutional trust variable is constructed as the sum of seven variables referring to trust in political institutions, civil security institutions and, supranational political institutions. In line with the hypothesis formed here, the results indicate the presence of endogeneity in the social and institutional trust interrelationship. When accounted for, this endogeneity entails different results as regards the sign of the effect that institutional trust exerts upon social trust, which turns from positive to negative. The study contributes to the limited empirical knowledge regarding the micro level two-way causal relationship between social trust and institutional trust. The study’s findings provides us with a more informative and accurate picture of the underlying dynamics of building trust in a society. Important research and policy level issues draw from these findings.

     

Reconceptualizing and expanding the positive feedback network effects model: A case study

During the 1980s, economists developed the concept of positive network effects and switching costs as the key dynamics of de facto standards competition. They concluded that a positive feedback loop usually “tips” a market to the standard with the most users and complementary assets. While recent scholars have acknowledged that not all markets tip, and suggested some possible limitations on this phenomena, these limitations have not been integrated systematically into a model for competition in these industries. Using examples drawn from the standards contests of the past 20 years, this case study develops an integrated model for competition in these industries.     

Interpreting MSHA Citations Through the Lens of Occupational Health and Safety Management Systems: Investigating Their Impact on Mine Injuries and Illnesses 2003–2010

Since the late 1980s, the U.S. Department of Labor has considered regulating a systems approach to occupational health and safety management. Recently, a health and safety management systems (HSMS) standard has returned to the regulatory agenda of both the Occupational Safety and Health Administration (OSHA) and the Mine Safety and Health Administration (MSHA). Because a mandated standard has implications for both industry and regulating bodies alike, it is imperative to gain a greater understanding of the potential effects that an HSMS regulatory approach can have on establishment‐level injuries and illnesses. Through the lens of MSHA's regulatory framework, we first explore how current enforcement activities align with HSMS elements. Using MSHA data for the years 2003–2010, we then analyze the relationship between various types of enforcement activities (e.g., total number of citations, total penalty amount, and HSMS‐aligned citations) and mine reportable injuries. Our findings show that the reduction in mine reportable injuries predicted by increases in MSHA enforcement ranges from negligible to 18%. The results suggest that the type and focus of the enforcement activity may be more important for accident reduction than the total number of citations issued and the associated penalty amount.     

Popular Hazards and Policy Rhetoric

Popular hazards are common activities that involve some risks of harm, such as driving a car, possessing or shooting a gun, drinking alcohol, or smoking marijuana. In each of these cases, many millions of Americans engage in the activity, but only a small fraction of them harm themselves or other people. Because the activity is so common, the number harmed may be substantial, although more serious harms tend to be much more infrequent than less serious harms. Social policy debates almost always focus on some particular popular hazard, yet we can see rhetorical similarities—parallel arguments—in how advocates frame what are understood to be very different social issues. Thus, discourse about legalizing recreational marijuana use tends to invoke claims that are quite similar to those opposing further gun control. The category of popular hazards allows us to recognize parallels in policy debates about seemingly unrelated social issues. Focusing on the underlying policy issue—balancing popularity and hazardousness—encourages considering alternative ways to construct social policies.     

The effect of earthworms on roadway-derived Zn deposited as a surface layer in storm water retention basin soils

Increased urban development, including an increase in impervious surfaces has the potential to alter the biogeochemistry of surface systems due to storm water runoff contaminated with potentially toxic trace metals (e.g. Zn, Cu and Pb). A major source for urban metals is dust that accumulates on roadways. This roadway dust is derived from vehicle wear sources and tends to be enriched in trace metals such as Pb, Zn, Cu, Cd, Ni and Cr. This continuous source is then being transported via storm water runoff to receiving systems, such as storm water retention systems, which become important focusing environments for trace metal deposition. The fate of these roadway derived metals and their bioavailability once deposited in these urban ecosystems is not well understood. In this investigation we tested the hypothesis that the distribution and form of surface deposited roadway-derived Zn is a function of earthworm processes and is species dependent. The results of this investigation indicate that roadway dust derived Zn deposited as a surface layer on urban soils is readily removed from the surface in less than 30 days whether earthworms are present or not. However, after 90 days, the presence of earthworms and the life habit of the earthworm species present was found to have a significant impact on the physical and chemical cycling of roadway derived trace metals in storm water retention basin soils.     

Gifts, Cash, and Stigma

Each year individuals in the United States transfer between $50 and $72 billion in resources in the form of noncash holiday gifts, despite the fact that holiday gift recipients apparently value their noncash gifts at about 10% less than the prices paid by the givers. We document that cash giving is more likely from givers who tend to give unwanted gifts, indicating that givers are concerned with the utility of their recipients. The rarity of cash gifts can be rationalized by a stigma of cash giving that we are able to parameterize and estimate using a simple structural model.