Conditional Monte Carlo Gradient Estimation in Economic Design of Control Limits

The economic approach to determining the optimal control limits of control charts requires estimating the gradient of the expected cost function. Simulation is a very general methodology for estimating the expected costs, but for estimating the gradient, straightforward finite difference estimators can be inefficient. We demonstrate an alternative approach based on smoothed perturbation analysis (SPA), also known as conditional Monte Carlo. Numerical results and consequent design insights are obtained in determining the optimal control limits for exponentially weighted moving average and Bayes charts. The results indicate that the SPA gradient estimators can be significantly more efficient than finite difference estimators, and that a simulation approach using these estimators provides a viable alternative to other numerical solution techniques for the economic design problem.     

Unquestioned Answers or Unanswered Questions: Beliefs About Science Guide Responses to Uncertainty in Climate Change Risk Communication

In two experimental studies we investigated the effect of beliefs about the nature and purpose of science (classical vs. Kuhnian models of science) on responses to uncertainty in scientific messages about climate change risk. The results revealed a significant interaction between both measured (Study 1) and manipulated (Study 2) beliefs about science and the level of communicated uncertainty on willingness to act in line with the message. Specifically, messages that communicated high uncertainty were more persuasive for participants who shared an understanding of science as debate than for those who believed that science is a search for absolute truth. In addition, participants who had a concept of science as debate were more motivated by higher (rather than lower) uncertainty in climate change messages. The results suggest that achieving alignment between the general public's beliefs about science and the style of the scientific messages is crucial for successful risk communication in science. Accordingly, rather than uncertainty always undermining the effectiveness of science communication, uncertainty can enhance message effects when it fits the audience's understanding of what science is.     

Measuring underemployment and inequality in the work force

In a recent article in this journal, Tipps and Gordon (1985) presented new indicators of underemployment and compared them to indicators obtained from the Labor Utilization Framework (LUF) of Hauser, Sullivan, Clogg, and others. In this note the Tipps-Gordon criticisms of LUF are reviewed, the Tipps-Gordon framework is criticized, and both LUF and the Tipps-Gordon approach are compared empirically as well as conceptually. An extension of LUF is also presented.     

Social media,temporality, and the legitimacy of protest

ABSTRACT

This article examines how the rise of social media affects the temporal relations of protest communication. Following a relational approach, it traces how regimes of temporality are constructed and transformed through the entanglement between media infrastructures, institutions, and practices. These regimes involve particular ‘speeds’ -the rate at which media content is renewed – as well as ‘temporal orientations’ towards present, past, and future. The article questions how specific temporal regimes enable or complicate protestors’ efforts to gain public legitimacy. A large body of research suggests that it is difficult to gain such legitimacy in the mainstream news cycle, in which protest is primarily covered from an ‘episodic’ perspective, ignoring larger protest issues. The present analysis suggests that despite the participatory affordances of social media, it has not become any easier to generate sustained public attention for structural protest issues. Drawing examples from three case studies, it demonstrates that the dominant mode of social media protest communication reproduces and reinforces the episodic focus of the mainstream news. While other temporal perspectives on protest are certainly developed in the alternative and mainstream news, as well as in activist social media communication, these do not fundamentally challenge the prevailing temporal orientation towards the present, towards the event.     

New dawn or end of labour?: from South Africa’s East Rand to Ekurhuleni

ABSTRACT

The question raised in this article is whether the key role played under apartheid by labour in the transition to democracy can be revived in the struggle against the persistent and deepening inequality of the post-apartheid period. We argue that the transition to a neoliberal state in the post-apartheid period has fragmented workers and weakened their capacity to build sustainable workplace organization. However, in spite of this, we identify the emergence of collective action and organization amongst these precarious workers. We show how in response to the degeneration of their traditional organizations, these workers are rebuilding worker organization still very much inscribed in the organizational traditions built on the East Rand over 40 years ago. We challenge the pessimistic ‘end of labour’ thesis that suggests that the informalization of employment has made collective organization impossible.     

Body image,self-esteem,and behavioral risk for chronic disease among college students: Additional evidence for integrated prevention

Abstract

Objective: To examine associations between two body image constructs (body appreciation and body satisfaction) and five health behaviors (diet, physical activity, weight management, tobacco exposure, and alcohol intake) associated with risk for chronic disease, controlling for self-esteem. Participants: Three hundred and forty-four college students enrolled at a large, public university in the southeastern US. Methods: Students completed an online survey composed of measures of body appreciation, body satisfaction, self-esteem, and frequency of engagement in preventive health behaviors. Hierarchical linear regression models were used to assess relationships between constructs. Results: Body appreciation, but not body satisfaction or self-esteem, significantly and positively predicted engagement in diet-, physical activity-, and weight-related health behaviors. No associations were found for substance use outcomes. Conclusions: Results illuminate health risks among college students and provide additional evidence to support the development of holistic preventive interventions that simultaneously address aspects of mental and physical health among college students.     

Temporal Dynamics Linking Aspects of Parent Monitoring with Early Adolescent Antisocial Behavior

This longitudinal study examined the covariation between parents' use of control and solicitation, youth willingness to self-disclose to parents, and youth antisocial behavior from ages 13 to 14. Structural equation analyses were conducted on a combined sample of Italian (N  =  152) and French Canadian (N  =  151) adolescents. Analyses tested for longitudinal cross-lagged effects while controlling for stability and all concurrent associations. Although bivariate correlations showed consistent associations among these constructs, both concurrently and over one year, SEM results revealed virtually no cross-lagged effects, after controlling for concurrent associations and stability. These findings suggest that the actual causal effects of parenting and youth behavior may best be conceptualized as occurring in the moment, rather than over extended periods of time. Results also showed that parental control and solicitation demonstrated very different associations with youth antisocial behavior, and should therefore be considered separately for research and prevention.     

A review of empirical research on dynamic competitive strategy

Beginning with Chandler's 1962 seminal work, researchers have emphasized that competitive strategy is not a static phenomenon, but rather a sequence of interconnected actions and reactions unfolding over time. This paper reviews the empirical research on dynamic competitive strategy published between 1986 and 2005 in nine leading strategic management journals. An integrated framework is used to showcase the research in terms of antecedents, strategic actions and outcomes. The literature review demonstrates that significant progress has been made in the field of dynamic competitive strategy, and yet that there are still many promising lines of inquiry for future theoretical and empirical research, particularly in the areas of strategic action timing and path dependency.