Markov Chain Monte Carlo in small worlds

As the number of applications for Markov Chain Monte Carlo (MCMC) grows, the power of these methods as well as their shortcomings become more apparent. While MCMC yields an almost automatic way to sample a space according to some distribution, its implementations often fall short of this task as they may lead to chains which converge too slowly or get trapped within one mode of a multi-modal space. Moreover, it may be difficult to determine if a chain is only sampling a certain area of the space or if it has indeed reached stationarity. In this paper, we show how a simple modification of the proposal mechanism results in faster convergence of the chain and helps to circumvent the problems described above. This mechanism, which is based on an idea from the field of “small-world” networks, amounts to adding occasional “wild” proposals to any local proposal scheme. We demonstrate through both theory and extensive simulations, that these new proposal distributions can greatly outperform the traditional local proposals when it comes to exploring complex heterogenous spaces and multi-modal distributions. Our method can easily be applied to most, if not all, problems involving MCMC and unlike many other remedies which improve the performance of MCMC it preserves the simplicity of the underlying algorithm.     

The production of therapy:the social process of construction of the mother of a sexually abused child

This study qualitatively examined the perspectives of clinical social workers on non-offending mothers of sexually abused children. The study examined whether clinicians still used collusion to explain mothers' behavior, despite research refuting collusion. Findings revealed that, although workers did not use collusion, they still constructed mothers negatively. Multiple contexts of agency practice influenced constructions. Administrative use of authority to implement external constraints led to workers' resistance, which involved humor with gender and ethnic components. The agency's role as a graduate social work teaching site contributed the following: Field instructors transmitted the belief that incest typified severe family difficulties and posed complex assessment and intervention problems. Implications for effective practice are discussed.     

COST-VOLUME-PROFIT ANALYSIS IN STOCHASTIC PROGRAMMING MODELS

This paper applies mathematical programming to cost-volume-profit (CVP) analysis under contribution margin uncertainty. Three CVP probabilistic chance-constraint models based on various safety-first criteria for decisions under uncertainty are presented and compared. It is shown that a break-even segment of the mean-standard deviation frontier is a set of optimal solutions for the proposed models. An operational parametric quadratic programming (QP) model is constructed, and the efficiency frontier is generated. The procedures for locating an optimal solution on the efficiency frontier are then presented. The recommended QP procedure offers both technical relief from the computational difficulties posed by the probabilistic constraints and a desired flexibility in generating and presenting the relevant information for decisions under uncertainty.     

Computer‐Mediated Communication in Intimate Relationships: Associations of Boundary Crossing,Intrusion, Relationship Satisfaction,and Partner Responsiveness

This study examined the impact of technology on couples in committed relationships through the lens of the couple and technology framework. Specifically, we used data from 6,756 European couples to examine associations between online boundary crossing, online intrusion, relationship satisfaction, and partner responsiveness. The results suggest that participants’ reports of online boundary crossing were linked with lower relationship satisfaction and partner responsiveness. Also, lower relationship satisfaction and partner responsiveness were associated with increased online boundary crossing. The results suggest that men, but not women, who reported greater acceptability for online boundary crossing were more likely to have partners who reported lower relationship satisfaction in their relationships. Implications for clinicians, relationship educators, and researchers are discussed.     

Determinants of public attitude towards a social enterprise crisis in the digital era: Lessons learnt from THINX

This study examines how the perceived locus of crisis cause, controllability, and adherence to social mission are associated with public attitude in the context of a social enterprise crisis and evaluates the differences between these variables under episodic and thematic frames of online articles. Using the crisis case of THINX in 2017 as a case study, a quantitative content analysis was performed on a sample of 503 comments under online articles. Hierarchical regression revealed that the locus of crisis cause and adherence to social mission were associated with public attitude, whereas controllability was not associated with public attitude when adherence to social mission was accounted for. Significant differences were found in the locus of crisis cause, controllability, adherence to social mission, and public attitude between episodic and thematic frames. This study provided a basis for the theoretical development of crisis communication in a social enterprise and the corresponding role for public relations.