Model-based clustering for social networks

Summary.  Network models are widely used to represent relations between interacting units or actors. Network data often exhibit transitivity, meaning that two actors that have ties to a third actor are more likely to be tied than actors that do not, homophily by attributes of the actors or dyads, and clustering. Interest often focuses on finding clusters of actors or ties, and the number of groups in the data is typically unknown. We propose a new model, the latent position cluster model , under which the probability of a tie between two actors depends on the distance between them in an unobserved Euclidean 'social space', and the actors' locations in the latent social space arise from a mixture of distributions, each corresponding to a cluster. We propose two estimation methods: a two-stage maximum likelihood method and a fully Bayesian method that uses Markov chain Monte Carlo sampling. The former is quicker and simpler, but the latter performs better. We also propose a Bayesian way of determining the number of clusters that are present by using approximate conditional Bayes factors. Our model represents transitivity, homophily by attributes and clustering simultaneously and does not require the number of clusters to be known. The model makes it easy to simulate realistic networks with clustering, which are potentially useful as inputs to models of more complex systems of which the network is part, such as epidemic models of infectious disease. We apply the model to two networks of social relations. A free software package in the R statistical language, latentnet, is available to analyse data by using the model.     

Going most of the way: “Technical virginity” among American adolescents

Reports from academic and media sources assert that many young people substitute non-vaginal sexual activities for vaginal intercourse in order to maintain what could be called “technical virginity.” Explanations for technical virginity, however, are based on weak empirical evidence and considerable speculation. Using a sample of 15–19-year-olds from Cycle 6 of the National Survey of Family Growth, we examine technical virginity and its motivations. The results suggest that religious adolescents are less likely than less-religious ones to opt for non-vaginal sex over total abstinence. Abstinence pledgers who are virgins are neither more nor less likely than nonpledgers who are virgins to substitute non-vaginal sex for intercourse. Moreover, religion and morality are actually the weakest motivators of sexual substitution among adolescents who have not had vaginal sex. Preserving technical virginity is instead more common among virgins who are driven by a desire to avoid potential life-altering consequences, like pregnancy and sexually transmitted diseases.     

Discourses about Righting the Business ← → Society Relationship

This article engages the question—what is the right business‐society relationship? We consider three perspectives that seek to address the relationship: corporate social responsibility (CSR), social entrepreneurship (SE), and conscious capitalism (CC). We take a macroapproach considering how commentary about these approaches establishes a direction for corporate practice and its relationship to key stakeholder groups. We argue that these perspectives are ‘D'iscourses that provide arguments for and articulations about the direction of corporate practice and the business‐society relationship. To organize our review of each perspective, and focus our critique, for each we highlight (a) drivers and influencers, (b) core assumptions and defining features, and (c) approaches and exemplars. Although distinct, all emphasize effective business practices as key to meeting social needs. CSR suggests legitimizing business practice; SE relocates business practices; and CC seeks to reimagine/rehabilitate business for social good. Ultimately, we conclude that these Discourses lack a clear communicative focus in terms of decision making within these organizations. We attend to this and other implications, and offer avenues for further research.     

Creating Tactile Space during a University Extension Field Day Event: The Case of a Sustainable Agriculture Innovation

Drawing on the concept of “tactile space,” we evaluate the experiential learning environment of a university extension field day event focused on a sustainable agriculture innovation: biodegradable plastic mulch. Introduced by sociologist Michael Carolan, “tactile spaces” are sensuously rich learning environments where participants interact with each other and the environment in an “embodied” and “embedded” manner leading to long‐lasting attitudinal and behavioral change. In our study, farmers, extension professionals, crop consultants, and mulch manufacturers participated in a field day event designed to provide both embodied and embedded experiences in an effort to stimulate interest in biodegradable plastic mulch, an economically and environmentally sustainable alternative to polyethylene mulch. Field day participants engaged in hands‐on demonstrations preceded and followed by focus group sessions. Enhancing the learning environment in these ways improved the success of the field day event by encouraging practice‐based forms of learning, which supplemented and reinforced the claims made about biodegradable plastic mulch. However, the tactile space could have been enriched by providing more opportunities for participants to become embedded within the environment, and by adding elements to overcome the temporal limitations of the field day event. This research contributes to the broader literature on participatory research and extension.     

Deepwater Horizon Oil Spill Exposure,Industry Sector,and Child Health

Population Research and Policy Review - The historic 2010 BP Deepwater Horizon Oil Spill (DHOS) led to public distress regarding potential impacts on children in nearby Gulf Coast communities....     

Metropolitan influences on migration into poor and nonpoor neighborhoods

Data from the Panel Study of Income Dynamics and three decennial US censuses are used to examine the influence of metropolitan-area characteristics on black and white households’ propensity to move into poor versus nonpoor neighborhoods. We find that a nontrivial portion of the variance in the odds of moving to a poor rather to a nonpoor neighborhood exists between metropolitan areas. Net of established individual-level predictors of inter-neighborhood migration, black and white households are more likely to move to a poor or extremely poor tract rather than to a nonpoor tract in metropolitan areas containing many poor neighborhoods and a paucity of recently-built housing in nonpoor areas. Blacks are especially likely to move to a poor tract in metropolitan areas characterized by high levels of racial residential segregation and in which poor tracts have a sizeable concentration of blacks. White households are more likely to move to a poor than to a nonpoor tract in metropolitan areas that have comparatively few African Americans.     

Bad news indeed for Ryff’s six-factor model of well-being

Springer and Hauser (An Assessment of the Construct Validity of Ryff’s Scales of Psychological Well-Being: Method, Mode, and Measurement Effects. 2006. Social Science Research 35) tested one key aspect of the validity of Ryff’s six-factor model of psychological well-being (RPWB), namely, whether there is substantial independent variation among the six factors. In several large and heterogeneous samples, under a variety of model specifications, and using various sets of RPWB items, we found very high factor correlations among the dimensions of well-being, especially personal growth, purpose in life, self-acceptance, and environmental mastery. That is, the six-factor model makes theoretical claims that do not yield large or consistent empirical distinctions when standard measures and instrumentation are used. Where Ryff and Singer’s comment (Best News Yet on the Six-Factor Model of Well-Being. 2006. Social Science Research 35) refers directly to that analysis, their methodological discussion is most often irrelevant or incorrect. Their text largely ignores and fails to challenge our strong empirical findings about the factorial structure of well-being. In this response, we reinforce these findings and their implications for the (in)validity of the six-factor well-being model as implemented by Ryff. We also explain why Ryff and Singer’s lengthy review of studies that show differential relationships of RPWB factors with other variables should be interpreted with far greater caution than Ryff and Singer recognize. We offer recommendations for analyzing RPWB items in surveys that have already been conducted, but we also emphasize the need for a thorough rethinking of the measurement and dimensionality of psychological well-being.     

Variance Function Regression in Hierarchical Age-Period-Cohort Models: Applications to the Study of Self-Reported Health

Two long-standing research problems of interest to sociologists are sources of variations in social inequalities and differential contributions of the temporal dimensions of age, time period, and cohort to variations in social phenomena. Recently, scholars have introduced a model called Variance Function Regression for the study of the former problem, and a model called Hierarchical Age-Period-Cohort regression has been developed for the study of the latter. This article presents an integration of these two models as a means to study the evolution of social inequalities along distinct temporal dimensions. We apply the integrated model to survey data on subjective health status. We find substantial age, period, and cohort effects, as well as gender differences, not only for the conditional mean of self-rated health (i.e., between-group disparities), but also for the variance in this mean (i.e., within-group disparities)-and it is detection of age, period, and cohort variations in the latter disparities that application of the integrated model permits. Net of effects of age and individual-level covariates, in recent decades, cohort differences in conditional means of self-rated health have been less important than period differences that cut across all cohorts. By contrast, cohort differences of variances in these conditional means have dominated period differences. In particular, post-baby boom birth cohorts show significant and increasing levels of within-group disparities. These findings illustrate how the integrated model provides a powerful framework through which to identify and study the evolution of variations in social inequalities across age, period, and cohort temporal dimensions. Accordingly, this model should be broadly applicable to the study of social inequality in many different substantive contexts.     

THE ETHICS AND POLITICS OF MUTUAL OBLIGATION

Welfare schemes which require recipients of benefits to ‘give something back’ are often justified in terms of ‘fairness’ or fulfilling the ‘social contract’. The Australian Government's recent and proposed changes to unemployment benefits through the Mutual Obligation Scheme appeal to both justifications. However, insufficient attention has been paid the underlying ethical and political assumptions — a serious deficiency. given their role in legitimating harsh new penalties. There are two broad reasons the current trend to tie benefits to obligations is inappropriate. First, the unemployed have little choice about their contract. And second, there is insufficient mutuality shown towards the unemployed for the Scheme to be obligation‐generating. Rather than being a means of encouraging participation or mutuality, the Scheme is essentially punitive.     

Behavioral Stability Across Time and Situations: Nonverbal Versus Verbal Consistency

Behavioral consistency has been at the center of debates regarding the stability of personality. We argue that people are consistent but that such consistency is best observed in nonverbal behavior. In Study 1, participants’ verbal and nonverbal behaviors were observed in a mock interview and then in an informal interaction. In Study 2, medical students’ verbal and nonverbal behaviors were observed during first- and third-year clinical skills evaluation. Nonverbal behavior exhibited consistency across context and time (a duration of 2 years) whereas verbal behavior did not. Discussion focuses on implications for theories of personality and nonverbal behavior.