The Persistence of High Levels of Living Alone Among Adults with Disabilities in Sweden, 1993–2011

Population Research and Policy Review - This study investigates how the probability to live alone has developed among working age individuals with and without disabilities in Sweden during the...     

The Challenges in Developing an Online Applied Statistics Program: Lessons Learned at Penn State University

Numerous professional fields have an increasing need for individuals trained in statistics and other quantitative analysis techniques. Today there exists great potential to fulfill this need by providing opportunities through online learning. However, to provide a high-quality education for returning adult professionals seeking advanced degrees in applied statistics online, many challenges need to be overcome. Based on our experience developing Penn State University’s online program in applied statistics, we discuss the evolution of the program’s curriculum, recruitment and development of online faculty, and meeting the requirements of students as important areas that require consideration in the development of an online program. We also highlight program evaluation strategies employed to ensure innovation and improvement in online education as cornerstones to a program’s success.     

Social,Relational and Network Determinants of Unprotected Anal Sex and HIV Testing Among Men Who Have Sex with Men in Beirut,Lebanon

Objectives: We examined the social, relational and network determinants of condom use and HIV testing among men who have sex with men (MSM) in Beirut. Methods: Two-hundred thirteen men were recruited via respondent driven sampling and administered a survey. Results: Sixty-four percent reported unprotected anal intercourse (UAI), including 23% who had UAI with unknown HIV status partners (UAIU); 62% of participants had tested for HIV. In multivariate analysis, being in a relationship was associated with UAI and HIV testing; lower condom self-efficacy was associated with UAIU and HIV testing; gay discrimination was associated with UAIU; MSM disclosure was associated with UAI, UAIU and HIV testing; and network centralization was associated with HIV testing. Conclusions: Multi-level social factors influence sexual health in MSM.     

The Relationship Between Nonsuicidal Self‐Injury and Family Functioning: Adolescent and Parent Perspectives

We explored parent and adolescent reports of family functioning, how this differed if the parent was aware that their child self‐injured, and how parental awareness of self‐injury was related to self‐injury frequency, self‐injury severity, and help seeking. Participants were 117 parent–adolescent dyads, in 23 of which the adolescent self‐injured. Adolescents who self‐injured reported poorer family functioning than their parents, but parents who did not know about their child's self‐injury reported similar functioning to parents whose children did not self‐injure. Parents were more likely to know that their child self‐injured when the behavior was severe and frequent. Help‐seeking was more likely when parents knew about self‐injury. Family‐based interventions which emphasize perspective‐taking could be used to effectively treat self‐injury.     

The Weight Function Lemma for graph pebbling

Graph pebbling is a network model for studying whether or not a given supply of discrete pebbles can satisfy a given demand via pebbling moves. A pebbling move across an edge of a graph takes two pebbles from one endpoint and places one pebble at the other endpoint; the other pebble is lost in transit as a toll. It has been shown that deciding whether a supply can meet a demand on a graph is NP-complete. The pebbling number of a graph is the smallest t such that every supply of t pebbles can satisfy every demand of one pebble byt a vertex. Deciding if the pebbling number is at most k is \(\Pi _2^\mathsf{P}\)-complete. In this paper we develop a tool, called the Weight Function Lemma, for computing upper bounds and sometimes exact values for pebbling numbers with the assistance of linear optimization. With this tool we are able to calculate the pebbling numbers of much larger graphs than in previous algorithms, and much more quickly as well. We also obtain results for many families of graphs, in many cases by hand, with much simpler and remarkably shorter proofs than given in previously existing arguments (certificates typically of size at most the number of vertices times the maximum degree), especially for highly symmetric graphs. Here we apply the Weight Function Lemma to several specific graphs, including the Petersen, Lemke, \(4\mathrm{th}\) weak Bruhat, and Lemke squared, as well as to a number of infinite families of graphs, such as trees, cycles, graph powers of cycles, cubes, and some generalized Petersen and Coxeter graphs. In doing so we partly answer a question of Pachter, et al., by computing the pebbling exponent of cycles to within an asymptotically small range. It is conceivable that this method yields an approximation algorithm for graph pebbling.     

DO BETTER INFORMED INVESTORS ALWAYS DO BETTER? A BUYBACK PUZZLE

We explore the value of private investment information using data from a singular source: auctions of yearling racehorses. Horse breeders possess superior information about their own horses and have strong financial incentives to buy the best of these back at auction. However, those they repurchase subsequently perform significantly worse on average, earning 30% less at the racetrack than horses purchased by outsiders. Moreover, this underperformance is concentrated in male horses, despite these being purchased exclusively for racing purposes. These puzzling findings cannot be explained by differences in horse risk or breeder abilities, or by nonfinancial objectives, or by behavioral or selection biases. (JEL G02, G11, G14, L83, D44)     

Integrative Family Therapy With Childhood Chronic Illness: An Ethics of Practice

A challenge for contemporary family therapists is negotiating differences between modern and postmodern frameworks in the practice context. Modernists espouse a systemic metaphor; use evidence‐based and interventive approaches, including strategic, structural‐ or solution‐focused techniques, and believe in the therapist's knowledge, expertise and power to influence individuals or families to change. On the other hand, postmodernists follow a social constructionist, dialogical or narrative paradigm, which identifies the main ingredient of therapy as language, conversation, understanding and the therapist's ‘not knowing’ stance in eliciting a person's expertise and story Yet many practitioners adopt a middle way between these paradigm polarities, one that is less theory‐driven and more pragmatic, flexible, integrative and practice‐based. This is consistent with evidence‐based practice and research demonstrating common factors across all therapies. The value of preserving systemic thinking in family therapy is recognised while reaching forward to a postmodern social constructionist and dialogical approach. The article describes this integrative stance in family therapy as paramodern based on an ethics of practice. This is illustrated by a detailed case study of integrative family therapy, which addresses anxiety, anger and sleeping issues associated with a chronic childhood illness called Perthe's disease.     

An Empirical Approach to Sufficient Similarity: Combining Exposure Data and Mixtures Toxicology Data

When assessing risks posed by environmental chemical mixtures, whole mixture approaches are preferred to component approaches. When toxicological data on whole mixtures as they occur in the environment are not available, Environmental Protection Agency guidance states that toxicity data from a mixture considered “sufficiently similar” to the environmental mixture can serve as a surrogate. We propose a novel method to examine whether mixtures are sufficiently similar, when exposure data and mixture toxicity study data from at least one representative mixture are available. We define sufficient similarity using equivalence testing methodology comparing the distance between benchmark dose estimates for mixtures in both data‐rich and data‐poor cases. We construct a “similar mixtures risk indicator”(SMRI) (analogous to the hazard index) on sufficiently similar mixtures linking exposure data with mixtures toxicology data. The methods are illustrated using pyrethroid mixtures occurrence data collected in child care centers (CCC) and dose‐response data examining acute neurobehavioral effects of pyrethroid mixtures in rats. Our method shows that the mixtures from 90% of the CCCs were sufficiently similar to the dose‐response study mixture. Using exposure estimates for a hypothetical child, the 95th percentile of the (weighted) SMRI for these sufficiently similar mixtures was 0.20 (i.e., where SMRI <1, less concern; >1, more concern).