Bayesian modelling of catch in a north-west Atlantic fishery

Summary. We model daily catches of fishing boats in the Grand Bank fishing grounds. We use data on catches per species for a number of vessels collected by the European Union in the context of the Northwest Atlantic Fisheries Organization. Many variables can be thought to influence the amount caught: a number of ship characteristics (such as the size of the ship, the fishing technique used and the mesh size of the nets) are obvious candidates, but one can also consider the season or the actual location of the catch. Our database leads to 28 possible regressors (arising from six continuous variables and four categorical variables, whose 22 levels are treated separately), resulting in a set of 177 million possible linear regression models for the log-catch. Zero observations are modelled separately through a probit model. Inference is based on Bayesian model averaging, using a Markov chain Monte Carlo approach. Particular attention is paid to the prediction of catches for single and aggregated ships.     

A Quantitative Assessment of the Risks from Illegally Imported Meat Contaminated with Foot and Mouth Disease Virus to Great Britain

Foot and mouth disease (FMD) is considered by many as the most important animal disease in the world. FMD is highly contagious and outbreaks incur significant costs as affected countries are severely limited in their ability to trade. A number of trade commodities may be contaminated with FMD virus (FMDV) including animal products, for example, meat. As a member of the European Union, Great Britain (GB) has put in place a number of regulations to prevent the importation of pathogens in imported meat products. However, the illegal importation of meat provides a route by which safety controls may be circumvented and meat from FMD affected areas may be imported. This study assesses the FMD infection risk posed to the livestock population of GB from the illegal importation of meat, and estimates the major contributors to this overall risk, through the development of a quantitative risk assessment model. From model results, the total amount of illegal meat entering GB each year is estimated on average to be 11,875 tonnes. with 90% certainty that this is between 4,398 and 28,626 tonnes per year; of which between 64.5 and 565 kg are contaminated with FMDV. This flow of illegal meat results in an estimate of a frequency of FMD infection in GB livestock of 0.015 cases of infected animals per year, with 90% certainty it is between 0.0017 and 0.053. Imports from the region Near and Middle East account for 47% of this risk, and 68% of the risk is attributed to bone-in and dried de-boned products.     

Discussion of “Nonparametric Bayesian Inference in Applications”: Bayesian nonparametric methods in econometrics

The use of Bayesian nonparametrics models has increased rapidly over the last few decades driven by increasing computational power and the development of efficient Markov chain Monte Carlo algorithms. We review some applications of these models in economic applications including: volatility modelling (using both stochastic volatility models and GARCH-type models) with Dirichlet process mixture models, uses in portfolio allocation problems, long memory models with flexible forms of time-dependence, flexible extension of the dynamic Nelson-Siegel model for interest rate yields and multivariate time series models used in macroeconometrics.     

The Indirect Effect of Child Maltreatment Severity on Adult PTSD Symptoms through Anxiety Sensitivity

Although the rate of posttraumatic stress disorder (PTSD) among survivors of child maltreatment is high, individuals differ in symptom severity and many do not experience clinically significant levels of psychopathology. The present study tested the indirect effects of child maltreatment severity on adult PTSD, suicidal ideations, and alcohol dependence via anxiety sensitivity. A sample of 336 participants (mean age of 22.81 years, SD = 8.93; 70.2% female) completed an online survey of child abuse and neglect, anxiety sensitivity, PTSD symptom severity, suicidal ideation severity, and alcohol dependence severity. The results revealed significant indirect effects of child maltreatment on PTSD symptom severity through cognitive and social concerns, but not physical concerns. No direct or indirect effects were demonstrated for suicidal ideations or alcohol dependence severity. These findings elucidate mechanisms in the robust relationship between child maltreatment and adult PTSD symptoms and can potentially inform future research on mechanisms of change in psychotherapy.     

Resources and strategies of interest groups and industry representatives involved in federal forest policy

This study analyzes the resources and strategies of public interest groups and industry representatives involved in federal forest policy in the state of Oregon during the early 1990s. While many studies have examined the role of interest groups in the policy process, few have compared empirically the resources available and strategies pursued by industry representatives and public interest groups in a particular policy domain. Utilizing survey data from 133 business representatives and 326 public interest groups involved in federal forest policy, the study argues that public interest group influence derives primarily from the ability to mobilize human resources; the financial resources of these groups tend to be modest. Industry and industry-supported groups, in contrast, possess considerable financial power while enjoying less support from the public. Consequently, industry interests tend to focus their efforts on more traditional forms of influence such as the persistent lobbying of natural resource agencies and elected officials. Public interest groups, in contrast, tend to devote considerable efforts to building public support in urban core areas to build the capacity to pressure governmental decision-makers.     

Exposure Assessment of TSEs from the Landspreading of Meat and Bone Meal

Recent changes in European legislation have meant that certain processed abattoir waste, which has been appropriately heat treated and ground to a specified particle size, can be spread on nonpasture agricultural land. This has opened the way for the potential landspreading of mammalian meat and bone meal (mMBM) derived from animals slaughtered for human consumption. This article reports on two separate case studies (Study 1 carried out in Great Britain (GB) and Study 2 carried out in Ireland) on the potential exposure to TSE infectivity following the spreading of abattoir waste (derived from animals slaughtered for human consumption) on nonpasture agricultural land. For Study 1, the average TSE infectivity on nonpasture agricultural land per year from sheep with scrapie was found to be higher (five orders of magnitude) than that estimated for BSE in cattle (3.9 x 10(-3) Ovine Oral ID(50)/ton of soil compared to 3.3 x 10(-8) Bovine Oral ID(50)/ton of soil). The mean estimate for BSE in sheep was 8.1 x 10(-6) Ovine Oral ID(50)/ton of soil. The mean level of infectivity in mMBM was assessed to be 1.2 x 10(-5) and 2.36 x 10(-5) ID(50)/ton of mMBM for Study 1 and 2, respectively. For Study 2 the spreading of mMBM was estimated to result in infectivity on nonpasture land of 1.62 x 10(-8) Bovine Oral ID(50)/m(3). The mean simulated probability of infection per year per bovine animal was 1.11 x 10(-9). Given the low infectivity density and corresponding low risks to bovines the spreading of mMBM could be considered a viable alternative for the utilization of mMBM.     

Reconsidering the Marielito Legacy: Race/Ethnicity,Nativity, and Homicide Motives*

Objective. This article investigates how race/ethnicity is associated with specific types of violent crime such as killings between intimates, robbery homicide, or drug‐related killings. We extend the study of the role of race and ethnicity for violence by examining five ethnic/immigrant groups, including the Mariel Cubans—a group singled out by many as particularly drug‐crime‐prone. Methods. Using 1980 through 1990 homicide data for the City of Miami, we use multinomial logistic regression to examine the association between race/ethnicity, nativity, and several types of homicide motives. Results. Contrary to popular expectations, ethnicity and immigration status rarely play a role in the types of homicide involvement of victims or violators. Incident characteristics, such as multiple offenders, or gender and age, were consistently more important influences in shaping homicide circumstances. Conclusions. The analyses revealed few significant relationships between immigration status and homicide motives, suggesting that immigrant groups like the Marielitos have more in common with native groups' experiences of criminal violence than is commonly assumed.     

Exclusion restrictions in instrumental variables equations

In this paper we consider two-stage estimators of parameters of a structural equation in a model with recursive exclusion restrictions on the instrumental variables equations. The estimations considered are simple OLS and GLS estimators after substitution of estimates of the systematic part of the IV equations for the endogenous variables. It is known in the literature that neither imposing the restrictions in the first stage nor ignoring them will in general be more efficient than the alternative. We introduce a class of mixed instrumental variables estimators (MIV) with these possibilities as special cases which yields an estimator which is not only more efficient than the two stage estimators considered in the literature but as efficient as an efficient system estimator like 3SLS.     

Personality Disorders Among Pathological Gamblers

The objective of this study was to investigate the prevalence of DSM-III-R diagnostic categories of personality disorders in pathological gamblers and to highlight the possible association between such disorders, psychological distress and selected forms of gambling. The Personality Disorders Questionnaire-Revised and a battery of psychometric measures were administered to a sample of 82 consecutive admissions to a behavioral treatment program for gambling problems at an impulse control disorders research unit in Sydney, Australia. Seventy-three percent of subjects were male. The total sample reported having gambled a mean of 15 years of which, on average, the last 6.4 years were associated with problems. Results indicated that the majority of subjects met diagnostic criteria for at least one Personality Disorder (93%), with an average of 4.6 personality disorders per subject. The majority of gamblers evidenced personality disorders from the Cluster B grouping with particularly high rates of borderline, histrionic, and narcissistic personality disorders which were found to be associated with high levels of impulsivity and affective instability. Antisocial personality disorder and narcissistic personality disorder were both found to be possible mediators of the severity of the problem gambling behaviours.