Bayesian inference for pairwise interacting point processes

Pairwise interacting point processes are commonly used to model spatial point patterns. To perform inference, the established frequentist methods can produce good point estimates when the interaction in the data is moderate, but some methods may produce severely biased estimates when the interaction in strong. Furthermore, because the sampling distributions of the estimates are unclear, interval estimates are typically obtained by parametric bootstrap methods. In the current setting however, the behavior of such estimates is not well understood. In this article we propose Bayesian methods for obtaining inferences in pairwise interacting point processes. The requisite application of Markov chain Monte Carlo (MCMC) techniques is complicated by an intractable function of the parameters in the likelihood. The acceptance probability in a Metropolis-Hastings algorithm involves the ratio of two likelihoods evaluated at differing parameter values. The intractable functions do not cancel, and hence an intractable ratio r must be estimated within each iteration of a Metropolis-Hastings sampler. We propose the use of importance sampling techniques within MCMC to address this problem. While r may be estimated by other methods, these, in general, are not readily applied in a Bayesian setting. We demonstrate the validity of our importance sampling approach with a small simulation study. Finally, we analyze the Swedish pine sapling dataset (Strand 1972) and contrast the results with those in the literature.     

Reports of Conferences, Institutes, and Seminars

This quarter's column features reports from the 2011 Electronic Resources & Libraries Conference; the 2011 North Carolina Serials Conference; the 2011 Association of College and Research Libraries Conference; the 2011 Kansas Library Association Conference; the New England Technical Services Librarians Section of the New England Library Association Spring 2011 Conference; and the 2011 Texas Library Association Conference.     

Identity Deployment and Social Change: Understanding Identity as a Social Movement and Organizational Strategy1

In this article, we discuss the theoretical implications of empirical elaborations of Bernstein’s (1997) model of identity deployment. New research encompasses a diverse array of venues and targets and elaborates on the mechanisms through which identities may be deployed strategically. Application of the identity deployment model spans a variety of so‐called ‘identity movements’ as well as ethnic, nationalist and indigenous movements, and community mobilization. Identity deployment is also a useful strategy in organizational and professional contexts, as in the micro‐brewery movement or culinary movements, demonstrating the theoretical generalizability of the original model. New research closely examines the relationship between identity and strategy and the conditions that affect activists’ choice of identity strategies as well as the situations where they might avoid identity strategies altogether. Research finds that identities may be deployed performatively, rhetorically or discursively. Identity deployment may be facilitated by emotional displays, music and ritual. The way that power and authority are organized in a given venue determines in part the capacity of activists and organizations to alternate between celebrating and suppressing difference from the majority. Identity deployment influences internal and external outcomes, affecting mobilization and goal achievement. Finally, feedback loops link the different analytic dimensions of identity.     

Positive and negative affect: A maximum-likelihood approach

Using the LISREL maximum-likelihood program, the relation between Bradburn's positive affect and negative affect scales is examined for three age groups of adults. It is found that (a) unequal item loadings fit significantly better than equal item loadings; (b) the best-fitting loadings for the elderly are significantly different from those of the non-elderly; (c) the positive and negative affect scales are substantially correlated and (d) correlations with related variables are stronger when positive and negative affect scales are formed by maximum-likelihood loadings rather than by unit loadings. Given the widespread use of Bradburn's scales, implications of these results for subjective well-being are discussed.     

Exploring self-care among dementia caregivers:the role of perceived support in accomplishing exercise goals

Support provided by family and friends may influence the extent to which older women who are primary caregivers for a spouse with dementia adhere to an exercise routine. The current study reports on qualitative interviews with 30 older female caregivers taking part in an exercise intervention regarding the support they received for their exercise goals. Results indicate that nearly all women received some level of verbal encouragement from family and friends, though far fewer had exercise partners or someone to stay with their husbands while they exercised. To reflect the wide variation observed in the amount of exercise support received and needed by caregivers, a typology of support situations was constructed as follows: Self-reliant, Well-supported, Under-supported, and Superfluous support. Implications for future exercise interventions targeting this population are discussed.     

Food insufficiency and physical and mental health in a longitudinal survey of welfare recipients

Food insufficiency is a significant problem in the United States, and poor African American women with children are at especially high risk. An inadequate household food supply can potentially affect the well-being of household members, but it is difficult to distinguish the effects of food insufficiency from risk factors for poor health that are also common among the food insufficient, such as poverty. We examined food insufficiency and physical and mental health among African American and white women (n = 676) who were welfare recipients in 1997. Controlling for common risk factors, women who reported food insufficiency in both 1997 and 1998 were more likely to report fair or poor health at the later date. Food insufficiency in 1998 was significantly associated with meeting the diagnostic screening criteria for recent major depression. Food insufficiency at both times and in 1998 only was related to women's sense of mastery. These findings add to growing evidence that household food insufficiency is associated with poor physical and mental health.     

Child welfare privatization: quantitative indicators and policy issues

The purpose of this study was to demonstrate the development of safety, permanency, and child well-being indicators by using administrative data sets as well as by using these indicators as tools for evaluating Florida's Community-Based Care (CBC) initiative. Longitudinal data from 37 counties including 4 counties that implemented community-based care were examined in this study. The results of the study indicated that the overall performance of CBC counties is at least as good as the performance of their comparison run by the state counties. The findings that emerged from this study may provide important lessons for developing a performance measurement system in the child welfare field.