An Approximate Bayesian Marginal Likelihood Approach for Estimating Finite Mixtures

Estimation of finite mixture models when the mixing distribution support is unknown is an important problem. This article gives a new approach based on a marginal likelihood for the unknown support. Motivated by a Bayesian Dirichlet prior model, a computationally efficient stochastic approximation version of the marginal likelihood is proposed and large-sample theory is presented. By restricting the support to a finite grid, a simulated annealing method is employed to maximize the marginal likelihood and estimate the support. Real and simulated data examples show that this novel stochastic approximation and simulated annealing procedure compares favorably with existing methods.     

Compassion Satisfaction,Compassion Fatigue,and Burnout: A Replication Study with Victim Advocates

Abstract

Past research has investigated the rates of compassion satisfaction (CS), compassion fatigue (CF), and burnout within health-care providers. Findings indicate higher levels of CS and lower levels of CF predict lower rates of burnout. The current study extended prior research by replicating past research findings, but with victim advocates. This study enrolled a national sample of 142 victim advocates. A hierarchal linear regression was run to test the research questions. In level 1, years of experience was not significant and only accounted for 1.1% of the variance in burnout. When adding CS, the model became significant (p?<?.001) and CS accounted for an additional 51.8% of the variance. When CF was added to the final model, it was significant (p?<?.001), and accounted for an additional 19.3% of the variance. When comparing the findings to past studies, our findings were similar; however, our study did find that CS and CF accounted for significantly more variance than past studies with health-care providers. Therefore, CS and CF might be greater predictors of burnout in victim advocates than in health-care providers. Future studies should aim to create interventions to increase CS and decrease CF, to reduce burnout.     

生活在上海

我喜欢教学,也喜欢教学给我带来的感受。当看到学生们渐渐取得进步,就会心生成就感,我想这就是我对工作的满意度吧。所有这些,给我带来的,是让我觉得在上海生活的每一天都很有意思。     

Penalties and payoffs: The short-term economic consequences of human capital acquisition for resettled refugees in the United States

The relationship between refugee investments in human capital and short-run economic outcomes may influence the extent to which refugees invest in human capital that is associated with positive future economic mobility. Using data from the Annual Survey of Refugees from 2016 and 2017 we assess the relationship between recent investments in human capital and hourly wages for employed refugees in the United States. Results suggest that recent job training has a positive effect on hourly wages. In contrast, enrollment in English classes and educational programmes have no short-term positive effects on hourly wages. When combined with the pressure resettled refugees experience to find employment quickly, these results suggest that the lack of short-term wage benefits from English language or educational courses may dissuade refugees from sufficiently investing in the amount of English language or education necessary to promote positive long-term economic mobility.     

Can Carbon Nanomaterials Improve CZTS Photovoltaic Devices? Evaluation of Performance and Impacts Using Integrated Life‐Cycle Assessment and Decision Analysis

In emergent photovoltaics, nanoscale materials hold promise for optimizing device characteristics; however, the related impacts remain uncertain, resulting in challenges to decisions on strategic investment in technology innovation. We integrate multi‐criteria decision analysis (MCDA) and life‐cycle assessment (LCA) results (LCA‐MCDA) as a method of incorporating values of a hypothetical federal acquisition manager into the assessment of risks and benefits of emerging photovoltaic materials. Specifically, we compare adoption of copper zinc tin sulfide (CZTS) devices with molybdenum back contacts to alternative devices employing graphite or graphene instead of molybdenum. LCA impact results are interpreted alongside benefits of substitution including cost reductions and performance improvements through application of multi‐attribute utility theory. To assess the role of uncertainty we apply Monte Carlo simulation and sensitivity analysis. We find that graphene or graphite back contacts outperform molybdenum under most scenarios and assumptions. The use of decision analysis clarifies potential advantages of adopting graphite as a back contact while emphasizing the importance of mitigating conventional impacts of graphene production processes if graphene is used in emerging CZTS devices. Our research further demonstrates that a combination of LCA and MCDA increases the usability of LCA in assessing product sustainability. In particular, this approach identifies the most influential assumptions and data gaps in the analysis and the areas in which either engineering controls or further data collection may be necessary.     

Defender–Attacker Decision Tree Analysis to Combat Terrorism

We propose a methodology, called defender–attacker decision tree analysis, to evaluate defensive actions against terrorist attacks in a dynamic and hostile environment. Like most game‐theoretic formulations of this problem, we assume that the defenders act rationally by maximizing their expected utility or minimizing their expected costs. However, we do not assume that attackers maximize their expected utilities. Instead, we encode the defender's limited knowledge about the attacker's motivations and capabilities as a conditional probability distribution over the attacker's decisions. We apply this methodology to the problem of defending against possible terrorist attacks on commercial airplanes, using one of three weapons: infrared‐guided MANPADS (man‐portable air defense systems), laser‐guided MANPADS, or visually targeted RPGs (rocket propelled grenades). We also evaluate three countermeasures against these weapons: DIRCMs (directional infrared countermeasures), perimeter control around the airport, and hardening airplanes. The model includes deterrence effects, the effectiveness of the countermeasures, and the substitution of weapons and targets once a specific countermeasure is selected. It also includes a second stage of defensive decisions after an attack occurs. Key findings are: (1) due to the high cost of the countermeasures, not implementing countermeasures is the preferred defensive alternative for a large range of parameters; (2) if the probability of an attack and the associated consequences are large, a combination of DIRCMs and ground perimeter control are preferred over any single countermeasure.     

Diverging Destinies: Maternal Education and the Developmental Gradient in Time With Children

Using data from the 2003?C2007 American Time Use Surveys (ATUS), we compare mothers?? (N = 6,640) time spent in four parenting activities across maternal education and child age subgroups. We test the hypothesis that highly educated mothers not only spend more time in active child care than less-educated mothers but also alter the composition of that time to suit children??s developmental needs more than less-educated mothers. Results support this hypothesis: not only do highly educated mothers invest more time in basic care and play when youngest children are infants or toddlers than when children are older, but differences across education groups in basic care and play time are largest among mothers with infants or toddlers; by contrast, highly educated mothers invest more time in management activities when children are 6 to 13?years old than when children are younger, and differences across education groups in management are largest among mothers with school-aged children. These patterns indicate that the education gradient in mothers?? time with children is characterized by a ??developmental gradient.??     

Welfare programs and the state economy

Welfare policy has been controversial and support is often drawn along political affiliation lines, the economic return of investment in welfare programs is frequently cited as a justification for new and expanded policies. To investigate the direct and indirect effects of welfare programs on economic performance, the authors develop a multilink approach, through employment and investment. The relationship is then tested with data from each of the United States from 1976 to 2006. Findings show welfare programs have no direct effect on a state's economy. Indirectly, welfare has a negative effect through investment, though the effect on employment is minimal.     

Betting the farm on high food prices: A consumer based approach to agriculture protection

Our question is quite simple: If agriculture protectionism is a product of economic development, why is agriculture protected at such varying degrees by otherwise similarly developed countries? Previous attempts to fit agriculture into general models of trade policy formation have relied exclusively on producer demand for protection and merely assume the associated demand for lower prices that might come from consumers. Not surprisingly, these previous studies add only minimally to this strange phenomenon. Our method turns this approach on its head by modeling the political strategy of agriculture protection on the costs incurred by the consumer. Taking both producers and consumers into account more accurately reflects the intent of extant theoretical models of protectionism. Our results show that using the consumer as the dependent variable provides more robust results on common independent variables. Recent global events show that consumer disapproval of agriculture policies should not be underestimated by political scientists or politicians.