On Optimality of Bayesian Wavelet Estimators

Abstract.  We investigate the asymptotic optimality of several Bayesian wavelet estimators, namely, posterior mean, posterior median and Bayes Factor, where the prior imposed on wavelet coefficients is a mixture of a mass function at zero and a Gaussian density. We show that in terms of the mean squared error, for the properly chosen hyperparameters of the prior, all the three resulting Bayesian wavelet estimators achieve optimal minimax rates within any prescribed Besov space     for p  ≥ 2. For 1 ≤  p  < 2, the Bayes Factor is still optimal for (2 s +2)/(2 s +1) ≤  p  < 2 and always outperforms the posterior mean and the posterior median that can achieve only the best possible rates for linear estimators in this case.     

Additive mixed models with approximate Dirichlet process mixtures: the EM approach

We consider additive mixed models for longitudinal data with a nonlinear time trend. As random effects distribution an approximate Dirichlet process mixture is proposed that is based on the truncated version of the stick breaking presentation of the Dirichlet process and provides a Gaussian mixture with a data driven choice of the number of mixture components. The main advantage of the specification is its ability to identify clusters of subjects with a similar random effects structure. For the estimation of the trend curve the mixed model representation of penalized splines is used. An Expectation-Maximization algorithm is given that solves the estimation problem and that exhibits advantages over Markov chain Monte Carlo approaches, which are typically used when modeling with Dirichlet processes. The method is evaluated in a simulation study and applied to theophylline data and to body mass index profiles of children.     

Changes in risky gambling prevalence among a New Zealand population cohort

Evidence suggests that problem gambling is an unstable state where gamblers move into and out of risk over time. This article looks at longitudinal changes in risky gambling and the factors associated with an increased risk (measured by the Problem Gambling Severity Index [PGSI]) in the current New Zealand context, which has experienced a doubling of the electronic gaming machine (EGM) market over the last two decades. Respondents from a nationally representative baseline sample (n = 2672) were recontacted two years later to assess changes in gambling behaviours. Among the 901 respondents reached at follow-up, average gambling risk increased over time, and the prevalence of those who had at least some level of gambling risk (i.e. low-risk or greater) more than doubled (from 4.7% to 12.4%). The majority (80.2%) of those who were at risk at follow-up had not been at risk at baseline. Multivariate linear regression analyses show that the predictors of low to moderate increased risk include Pacific ethnicity; high neighbourhood deprivation status; baseline frequent, continuous gambler type; baseline PGSI status; and playing EGMs. These findings highlight the need to develop theories of gambling addiction trajectories and to identify the earliest point along the trajectory where public health interventions should occur.     

Consistent Probabilistic Social Choice

Two fundamental axioms in social choice theory are consistency with respect to a variable electorate and consistency with respect to components of similar alternatives. In the context of traditional non‐probabilistic social choice, these axioms are incompatible with each other. We show that in the context of probabilistic social choice, these axioms uniquely characterize a function proposed by Fishburn (1984). Fishburn's function returns so‐called maximal lotteries, that is, lotteries that correspond to optimal mixed strategies in the symmetric zero‐sum game induced by the pairwise majority margins. Maximal lotteries are guaranteed to exist due to von Neumann's Minimax Theorem, are almost always unique, and can be efficiently computed using linear programming.     

Socioeconomic System of the Oil Boom and Rural Community Development in Western North Dakota

An oil boom is a complex social and economic phenomenon. The socioeconomic system presented in this article represents a novel effort to explicate boom impacts and changes, within a systems framework, at the community level to enhance community planning and development efforts. Most boomtown studies focus on longitudinal changes of a boom‐bust‐recovery cycle or social‐disruption‐based approaches. This article is an effort to demonstrate that longitudinal changes or social disruptions of a boom manifest through the interactions and interrelationships between social entities and stakeholders acting within the boom conditions and surrounding conditions. The socioeconomic system approach in this article analyzes the boom as a system, which provides a useful lens for many other rural communities currently experiencing unconventional oil and gas development in the United States. The socioeconomic system highlights five main challenges or factors that need to be addressed through community development strategies: develop affordable housing, invest in community infrastructure, expand public services, attract new businesses to the area, and develop better community integration strategies to build trust and unity within the community. This article is qualitative and exploratory in nature. As a result, it explicates the functions, structure, and relationships between system entities to provide a broader understanding of coherence, conflicts, and synergies within a system.     

Open Innovation in Nonprofit Sports Clubs

This research paper investigates open innovation—that is, the use of purposive inflows and outflows of knowledge in order to innovate—in the context of nonprofit sports clubs, and is based on the content analysis of semi-structured interviews held with representatives of eleven sports clubs. The study develops a framework that describes open innovation activities in nonprofit sports clubs as facets of four superordinate dimensions, namely permeability of the club’s boundary, application and implementation of open innovation practices, managerial competencies, and the environmental and organizational surroundings in which the club operates. Within these dimensions, subordinate facets such as commitment of the club’s president and the strategic use of coopetitive environments explain how and why sports clubs are successful at implementing innovations and how their nonprofit status (e.g., volunteer work) contributes to (or is in conflict with) innovation. The findings provide implications for nonprofit organizations inside and outside the sports sector.     

Home gardening practice in Pune (India), the role of communities,urban environment and the contribution to urban sustainability

Urban Ecosystems - Urban agriculture (UA) is regarded as an emerging tool and strategy for sustainable urban development as it addresses a wide array of environmental, economic and social...     

Missing time with parents: son preference among Asians in the USA

We study prevalence of son preference in families of East and South Asian origin living in the USA by investigating parental time investments in children using American Time Use Surveys. Estimates show that East and South Asian mothers spend an additional hour of quality time per day with their young (aged 0–2 years) sons than with young daughters; son preference in mothers’ time allocation declines as children get older. East and South Asian fathers’ time with young children is gender neutral. We find gender specialization in time with children aged 6–17 with fathers spending more time with sons and mothers spending more time with daughters.     

Adaptive information design for outdoor augmented reality

Augmented Reality focuses on the enrichment of the user's natural field of view by consistent integration of text, symbols and interactive three-dimensional objects in real time. Placing virtual objects directly into the user's view in a natural context empowers highly dynamic applications. On the other hand, this necessitates deliberate choice of information design and density, in particular for deployment in hazardous environments like military combat scenarios. As the amount of information needed is not foreseeable and strongly depends on the individual mission, an appropriate system must offer adequate adaptation capabilities. The paper presents a prototypical, vehicle-mountable Augmented Reality vision system, designed for enhancing situation awareness in stressful urban warfare scenarios. Tracking, as one of the most crucial challenges for outdoor Augmented Reality, is accomplished by means of a Differential-GPS approach while the type of display to attach can be modified, ranging from ocular displays to standard LCD mini-screens. The overall concept also includes envisioning of own troops (blue forces), for which a multi-sensor tracking approach has been chosen. As a main feature, the system allows switching between different information categories, focusing on friendly, hostile, unidentified or neutral data. Results of an empirical study on the superiority of an in-view navigation cue approach conclude the paper.