Domains of convergence for the EM algorithm: a cautionary tale in a location estimation problem

The EM algorithm is a popular method for maximizing a likelihood in the presence of incomplete data. When the likelihood has multiple local maxima, the parameter space can be partitioned into domains of convergence, one for each local maximum. In this paper we investigate these domains for the location family generated by the t-distribution. We show that, perhaps somewhat surprisingly, these domains need not be connected sets. As an extreme case we give an example of a domain which consists of an infinite union of disjoint open intervals. Thus the convergence behaviour of the EM algorithm can be quite sensitive to the starting point.     

TOWARD A SOCIOLOGY OF CULT FILMS: Reading Rocky Horror

This article provides a sociological reading of cult films, in particular, The Rocky Horror Picture Show. Cult films are secular documents, celebrated as sacred texts by audiences and used as shared foci to collectively create rituals and belief systems. They differ from popular re-releases, fad films, films with cult qualities, and critical cult films in that they involve typical people in atypical situations, sympathetic deviance, challenges to traditional authority, reflections of societal strains, and paradoxical and interpretable resolutions. Examination of the Rocky Horror text and the cult activities that occur during its viewing, reveal it as a paradoxical indictment and validation of traditional societal arrangements.     

Risk Modeling, Assessment, and Management of Lahar Flow Threat

The 1991 eruption of Mount Pinatubo in the Philippines is considered one of the most violent and destructive volcanic activities in the 20th century. Lahar is the Indonesian term for volcanic ash, and lahar flows resulting from the massive amount of volcanic materials deposited on the mountain's slope posed continued post-eruption threats to the surrounding areas, destroying lives, homes, agricultural products, and infrastructures. Risks of lahar flows were identified immediately after the eruption, with scientific data provided by the Philippine Institute of Volcanology, the U.S. Geological Survey, and other research institutions. However, competing political, economic, and social agendas subordinated the importance of scientific information to policy making. Using systemic risk analysis and management, this article addresses the issues of multiple objectives and the effective integration of scientific techniques into the decision-making process. It provides a modeling framework for identifying, prioritizing, and evaluating policies for managing risk. The major considerations are: (1) applying a holistic approach to risk analysis through hierarchical holographic modeling, (2) applying statistical methods to gain insight into the problem of uncertainty in risk assessment, (3) using multiobjective trade-off analysis to address the issue of multiple decisionmakers and stakeholders in the decision-making process, (4) using the conditional expected value of extreme events to complement and supplement the expected value in quantifying risk, and (5) assessing the impacts of multistage decisions. Numerical examples based on ex post data are formulated to illustrate applications to various problems. The resulting framework from this study can serve as a general baseline model for assessing and managing risks of natural disasters, which the Philippines' lead agency-the National Disaster Coordinating Council (NDCC)-and other related organizations can use for their decision-making processes.     

The strengths of close ties: Taiwanese online entrepreneurship,gender and intersectionality

This article examines entrepreneurs who have started innovative Internet and mobile technology companies in Taiwan because they are at the forefront of industrial changes in the country. Similar to findings in Europe and the USA, education and careers in technology in Taiwan remain dominated by men. However, I argue that the gender inequality of the sector is partly the result of the fact that small new enterprises rely on family support and close social networks. Few women are able to join the sector with male friends and colleagues due to the close social ties of the founding teams (homophily). Among my female interviewees, half have started their nascent companies with their husbands and male partners (husband and wife teams). However, gender, family backgrounds and childcare responsibilities affect both men and women, and the interviewees in my study were open in discussing these personal factors in relation to being entrepreneurs. This article argues that starting an Internet company is a family decision, discussed within the household. Intersectionality, not only gender, explains the founders’ decision to start a company, and their choice of co-founders.     

HPV vaccine acceptance among a sample of Southern men who have sex with men: A comparison of younger and older men

Objectives: Do short, online educational messages about the human papillomavirus (HPV) influence younger and older men who have sex with men (MSM) differently? Second, what are the HPV knowledge levels and risk perceptions of Southern MSM living outside of major metropolitan areas? Methods: This study draws on participants who completed an anonymous online survey asking about their knowledge, risk assessment, and vaccine acceptance regarding HPV. Results: Knowledge about HPV was low among the MSM in this study. After reading a one-page information intervention, vaccine acceptability increased by a statistically significant amount among both a Younger and Older cohort but risk perception only increased among the younger respondents. Single men regardless of age cohort reported sharper increases in perceived risk after the intervention, but relationship status did not produce significant differences in vaccine acceptability. Conclusion: Online, brief interventions may be effective means of increasing motivation to vaccinate among Southern MSM.     

An Examination of the Communication Styles Associated with Psychopathy and Their Influence on Observer Impressions

Psychopathic individuals are characterized as “intra-species predators”—callous, impulsive, aggressive, and proficient at interpersonal manipulation. For example, despite their high risk for re-offending, psychopathic offenders often receive early release on parole. While reputed to be social chameleons, research suggests that even naive observers can accurately infer high levels of psychopathic traits in others with very brief exposures to behavior, but accuracy degrades with extended observation. We utilized a lens model approach to examine the communication styles (emotional facial expressions, body language, and verbal content) of offenders varying in levels of psychopathic traits using “thin slice” video clips of psychological assessment interviews and to reveal which cues observers use to inform their evaluations of psychopathy. Psychopathic traits were associated with more (a) Duchenne smiles, (b) negative (angry) emotional language, and (c) hand gestures (illustrators). Further, psychopathy was associated with a marked behavioral incongruence; when individuals scoring high in psychopathic traits engaged in Duchenne smiles they were also more likely to use angry language. Naïve observers relied on each of these valid behavioral signals to quickly and accurately detect psychopathic traits. These findings provide insight into psychopathic communication styles, opportunities for improving the detection of psychopathic personality traits, and may provide an avenue for understanding successful psychopathic manipulation.     

Deep Uncertainties in Sea-Level Rise and Storm Surge Projections: Implications for Coastal Flood Risk Management

Sea levels are rising in many areas around the world, posing risks to coastal communities and infrastructures. Strategies for managing these flood risks present decision challenges that require a combination of geophysical, economic, and infrastructure models. Previous studies have broken important new ground on the considerable tensions between the costs of upgrading infrastructure and the damages that could result from extreme flood events. However, many risk-based adaptation strategies remain silent on certain potentially important uncertainties, as well as the tradeoffs between competing objectives. Here, we implement and improve on a classic decision-analytical model (Van Dantzig 1956) to: (i) capture tradeoffs across conflicting stakeholder objectives, (ii) demonstrate the consequences of structural uncertainties in the sea-level rise and storm surge models, and (iii) identify the parametric uncertainties that most strongly influence each objective using global sensitivity analysis. We find that the flood adaptation model produces potentially myopic solutions when formulated using traditional mean-centric decision theory. Moving from a single-objective problem formulation to one with multiobjective tradeoffs dramatically expands the decision space, and highlights the need for compromise solutions to address stakeholder preferences. We find deep structural uncertainties that have large effects on the model outcome, with the storm surge parameters accounting for the greatest impacts. Global sensitivity analysis effectively identifies important parameter interactions that local methods overlook, and that could have critical implications for flood adaptation strategies.     

Determinants and effects of formal target agreements: an empirical investigation of German firms

We investigate organizational determinants and performance effects of formal target agreements for employees based on the IAB establishment panel, a representative panel of German establishments. The results show that establishments with a high employee turnover rate, a large proportion of temporary workers, and a highly qualified workforce are significantly more likely to implement target agreements. Also, establishments with works councils installed are more likely to do so, controlling, among others, for firm size. Concerning organizational performance, we apply a first-difference and a fixed effects approach and find that establishments that implement target agreements achieve around 5 % higher total sales compared to firms that did not introduce this practice. Hence, organizations seem to benefit from the implementation of formal target agreements for employees.     

Nationwide Newspaper Coverage of Same-Sex Marriage: A Community Structure Approach

Using the community structure approach to compare coverage of same-sex marriage in leading U.S. newspapers in 35 major cities nationwide, all articles of 250+ words were sampled from a 5-year span of January 1, 2007, to June 23, 2011, for a total of 577 articles. Articles were coded for “prominence” and “direction,” and then combined into a “Media Vector” score for each newspaper, ranging from .4523 to ?.1067. Initial Pearson correlations revealed three clusters had significant relationships: stakeholder (stakeholder proportions correlating with favorable coverage of stakeholder concerns), buffer (privilege correlating with favorable coverage of human rights issues), and vulnerability (vulnerable populations correlating with coverage favoring their perspectives). The stakeholder cluster includes: (percentage 25–44: r = .506, p = .001; gay market index: r = .432, p = .005; percentage 65+: r = ?.397, p = .009; percentage voting Democratic: r = .335, p = .025; percentage voting Republican: r = ?.330, p = .026). The buffer hypothesis was also confirmed (percentage college educated: r = .465, p = .002; percentage family income of $100,000+: r = .383, p = .012; and percentage professional/technical occupations: r = .300, p = .040). One vulnerability indicator, percentage below the poverty line, was also confirmed (r = ?.297, p = .041). A varimax rotated factor analysis and regression yielded 2 factors accounting for more than 29% of the variance: privilege/gay marketing/political identity, 24%, and Evangelicals, 5%.