An approach for finding fully Bayesian optimal designs using normal-based approximations to loss functions

The generation of decision-theoretic Bayesian optimal designs is complicated by the significant computational challenge of minimising an analytically intractable expected loss function over a, potentially, high-dimensional design space. A new general approach for approximately finding Bayesian optimal designs is proposed which uses computationally efficient normal-based approximations to posterior summaries to aid in approximating the expected loss. This new approach is demonstrated on illustrative, yet challenging, examples including hierarchical models for blocked experiments, and experimental aims of parameter estimation and model discrimination. Where possible, the results of the proposed methodology are compared, both in terms of performance and computing time, to results from using computationally more expensive, but potentially more accurate, Monte Carlo approximations. Moreover, the methodology is also applied to problems where the use of Monte Carlo approximations is computationally infeasible.     

A Generalization to Bivariate Mittag–Leffler and Bivariate Discrete Mittag–Leffler Autoregressive Processes

A generalization of the Gaver and Lewis (1980 Gaver , D. P. , Lewis , P. A. W. ( 1980 ). First order autoregressive gamma sequences and point processes . Adv. Appl. Probab. 12 : 727 – 745 .[Crossref], [Web of Science ®] , [Google Scholar]) model of first-order autoregressive process with marginals as bivariate Mittag–Leffler distribution is obtained. A necessary and sufficient condition for stationarity of the process is established. Autoregressive process with marginals follow bivariate discrete Mittag–Leffler distribution is also developed. The unknown parameters of the processes are estimated and some numerical results of the estimations are given.     

Advances on a Decision Analytic Approach to Exposure-Based Chemical Prioritization

The volume and variety of manufactured chemicals is increasing, although little is known about the risks associated with the frequency and extent of human exposure to most chemicals. The EPA and the recent signing of the Lautenberg Act have both signaled the need for high-throughput methods to characterize and screen chemicals based on exposure potential, such that more comprehensive toxicity research can be informed. Prior work of Mitchell et al. using multicriteria decision analysis tools to prioritize chemicals for further research is enhanced here, resulting in a high-level chemical prioritization tool for risk-based screening. Reliable exposure information is a key gap in currently available engineering analytics to support predictive environmental and health risk assessments. An elicitation with 32 experts informed relative prioritization of risks from chemical properties and human use factors, and the values for each chemical associated with each metric were approximated with data from EPA's CP_CAT database. Three different versions of the model were evaluated using distinct weight profiles, resulting in three different ranked chemical prioritizations with only a small degree of variation across weight profiles. Future work will aim to include greater input from human factors experts and better define qualitative metrics.     

A Lean Six Sigma framework for the reduction of ship loading commercial time in the iron ore pelletising industry

Evidence suggests that specifically designed frameworks to implement Lean Six Sigma (LSS) projects to tackle particular problems are more effective than ‘generic’ versions. This paper proposes an implementation framework to effectively deploy LSS to improve a key operation and performance indicator, i.e. ship loading commercial time, of one of the largest world producer of iron ore. This article therefore contributes with a refined framework to effectively implement LSS, and documents its successful application and effectiveness within the context of the case organisation. The LSS framework and project contributed in helping the studied organisation to improve both the capability of its ship loading process and commercial time by more than 30%, resulting in operational savings in the range of $300,000 USD per year. The systematic nature of the framework proposed also helped the organisation to establish a standardised routine to improve its operations. Managerial implications exposing the challenges faced during the implementation of LSS are also discussed to serve as lessons learnt to be considered in other LSS projects. Managers and engineers incharge of improving operations and processes can benefit from this paper as it can be used as a guide to direct the conduction of LSS projects and the empirical application of its principles and tools.     

Social Psychological Factors in Lifestyle Change and Their Relevance to Policy

Crises in obesity and changes in the environment illustrate the need to change problematic behaviors and lifestyles in large segments of the population. This article uses social psychological theory and research to understand methods for facilitating lifestyle change. A basic assumption in the social psychological perspective is that the environment and the person interact to determine behavior. Both factors are important for understanding "upstream" and "downstream" approaches to lifestyle change ( McKinlay, 1993 ; Verplanken & Wood, 2006 ) and consideration of one factor without the other may be disastrous. We review evidence from within and outside of the health context to illustrate the upstream and downstream approaches and then describe implications for public policy and intervention. The evidence and recommendations encompass a wide range of behaviors, ranging from speeding and intoxicated driving to eating an unhealthy diet and energy conservation. When armed with the relevant social psychological theory and evidence, lifestyle change campaigns are likely to be successful.     

Regional asymmetries in monetary transmission: The case of South Africa

PPP is unlikely to hold instantaneously for all commodities across the different regions of a monetary area. It is therefore possible that monetary expansions or contractions will have different effects in different regions, if there are regional asymmetries in the monetary transmission mechanism. We estimate the size of such asymmetries across the nine provinces of South Africa over the period 1997–2005. There are large and statistically significant differences in the response of prices to monetary expansions and contractions. The problems arising from transmission mechanism asymmetries are not restricted to international monetary unions.     

When Memory is Better for Out-group Faces: On Negative Emotions and Gender Roles

Memory for in-group faces tends to be better than memory for out-group faces. Ackerman et al. (Psychological Science 17:836–840, 2006) found that this effect reverses when male faces display anger, supposedly due to their functional value in signaling intergroup threat. We explored the generalizability of this reverse effect. White participants viewed Black and White male or female faces displaying angry, fearful, or neutral expressions. Recognition accuracy for White male faces was better than for Black male faces when faces were neutral, but this reversed when the faces displayed anger or fear. For female targets, Black faces were generally better recognized than White faces, and female faces were better remembered when they displayed anger rather than fear, whereas male faces were better remembered when they displayed fear rather than anger. These findings are difficult to reconcile with a functional account and suggest (a) that the processing of male out-group faces is influenced by negative emotional expressions in general; and (b) that gender role expectations lead to differential remembering of male and female faces as a function of emotional expression.     

Critical Nexus or Pluralist Discipline? Institutional Ambivalence and the Future of Canadian Sociology

While some scholars believe in a transdisciplinary future for the social sciences and humanities, we argue that sociology would do well to maintain its disciplinary borders, while celebrating the plurality of its intellectual, social, and political content. Although a pluralist position can threaten disciplinary coherence and increase fragmentation, we argue the counterbalance ought to be convergence around shared institutional norms of knowledge production. Establishing these norms is not easy, since there is a great deal of institutional ambivalence at play in the field of sociology. As such, sociology is pushed and pulled between two poles of at least four major continuums of knowledge production, which include the following: (1) interdisciplinary versus discipline‐based research; (2) political versus analytical scholarship; (3) professional versus public/policy sociology; and (4) local/national versus global audiences. Since both sides of these ideal‐typical continuums contain their own pathologies, we propose adopting a balanced position to correct for the shortcomings of each. Rather than imposing one philosophical or theoretical paradigm for the field, we suggest that embracing the "chaos" of our diverse forms of knowledge and centralizing and integrating findings will serve to strengthen our collective efforts in the long term. Alors que certains chercheurs croient en un avenir transdisciplinaire pour les sciences sociales et humaines, nous soutenons qu'il serait préférable pour la sociologie de maintenir ses frontières disciplinaires, tout en célébrant la pluralité de son contenu intellectuel, social, et politique. Bien qu'une telle position pluraliste puisse menacer la cohérence disciplinaire et accroître la fragmentation, nous défendons l'idée que la contre‐balance doit converger vers des normes institutionnelles communes de production de connaissances. La mise en place de ces normes n'est pas chose aisée. Une large quantité d'ambivalence institutionnelle est en jeu dans le domaine de la sociologie. Ainsi nous tendons vers quatre grands continuums de production de connaissances : (1) la recherche interdisciplinaire en opposition à la recherche par discipline ; (2) une érudition politique en opposition à celle analytique ; (3) une sociologie professionnelle contre une sociologie publique / politique ; et (4) un public local / national contre un public mondial. Dans la mesure où deux côtés de ces continuums idéaux‐typiques contiennent leurs pathologies propres, nous proposons d'adopter une position équilibrée pour corriger les lacunes de chacun. Ceci devrait être mieux reflété dans nos systèmes de récompense. Plutôt que d'imposer un paradigme philosophique ou théorique pour un domaine en question, nous suggérons de prendre en considération le «chaos» de nos diverses formes de connaissances, tout en centralisant et en intégrant plus efficacement nos conclusions. Ceci permettra de renforcer nos efforts collectifs sur le long terme.