Improving the efficiency and robustness of nested sampling using posterior repartitioning

Statistics and Computing - In real-world Bayesian inference applications, prior assumptions regarding the parameters of interest may be unrepresentative of their actual values for a given dataset....     

Families,social life,and well-being at older ages

As people age, many aspects of their lives tend to change, including the constellation of people with whom they are connected, their social context, their families, and their health—changes that are often interrelated. Wave I of the National Social Life, Health, and Aging Project (NSHAP) has yielded rich information on intimate ties, especially dyads and families, and on social connections generally. Combined with extensive biological and other health measures, NSHAP enables researchers to address key questions on health and aging. We begin with recent findings on intimate dyads, then move to social participation, and finally to elder mistreatment. Among dyads, we find that whereas sexual activity drops sharply with age for both women and men, gender differences in partner loss as well as psychosocial and normative pressures constrain women’s sex more than men’s. However, surviving partnerships tend to be emotionally and physically satisfying and are marked by relatively frequent sex. In contrast to sex, nonsexual intimacy is highly prevalent at older ages, especially among women. Older adults are also socially resilient—adapting to the loss of social ties by increasing involvement with community and kin networks. Despite these social assets, older adults remain vulnerable to mistreatment. Overall, these findings yield a mixed picture of gender-differentiated vulnerabilities balanced by proactive adaptation and maintenance of social and dyadic assets.     

Household Headship and Academic Skills of Indian Children: A Special Focus on Gender Disparities

Using multivariate analyses and reading, mathematics and writing scores of children (aged 8–11 years) from a nationally representative sample, we find that children from female headed households either perform better or similar, but never worse than those from male headed households. Also, household fixed effect analysis reveals no gender disparity in academic scores of children belonging to female headed households, a case not true for children from male headed households. We relate this finding to gender parity in educational expenditure on children in female headed households against gender disparity in the same in households headed by males. Based on our findings we also offer some policy suggestions.     

„Solidarität“ in südasiatischen Gesellschaften

Taking South Asia as an example, it is shown how efforts to designate “solidarity” as a universally valid category are handicapped on the one hand by the ambiguity of the concept, on the other by its culture-specificity. Based on a linguistic, historical and social overview, it is demonstrated that the discourse parameters for “solidarity” as they dominate in the German language discourse are little suited for the South Asian reality. This leads to critical deliberations on the assumption that concepts and notions of the so-called West are to be seen as universally valid and universally binding.     

Some variations on constrained minimum enclosing circle problem

Given a set P of n points and a straight line L, we study three important variations of minimum enclosing circle problem as follows:

1. Computing k identical circles of minimum radius with centers on L, whose union covers all the points in P.
2. Computing the minimum radius circle centered on L that can enclose at least k points of P.
3. If each point in P is associated with one of the k given colors, then compute a minimum radius circle with center on L such that at least one point of each color lies inside it.

We propose three algorithms for Problem (i). The first one runs in O(nklogn) time and O(n) space. The second one is efficient where k?n; it runs in O(nlogn+nk+k ²log³ n) time and O(nlogn) space. The third one is based on parametric search and it runs in O(nlogn+klog⁴ n) time. For Problem (ii), the time and space complexities of the proposed algorithm are O(nk) and O(n) respectively. For Problem (iii), our proposed algorithm runs in O(nlogn) time and O(n) space.     

Maternal Cocaine Use and Infant Behavior

This study examined the impact of maternal cocaine use and associated risk factors such as polysubstance use, maternal functioning, and caregiving on affect regulation during infancy. Participants were 45 mother‐infant dyads (19 cocaine exposed and 26 control infants) recruited at birth. Observations and maternal reports of infant behavior were obtained at 2 and 7 months of age, along with measures of pre‐ and postnatal substance use, maternal functioning, and caregiving stability. Maternal cocaine use accounted for significant variance in infant positive affect at 2 months. Other substance use and gestational age predicted infant distress to novelty and arousal during developmental assessments. At 7 months, the impact of prenatal cocaine exposure on infant affect regulation was mediated by postnatal alcohol use and caregiving stability. These findings, if replicated, suggest that 1 pathway to later problem behavior reported among substance‐exposed children may be through early regulatory problems and the quality of postnatal caregiving.     

A survival-adjusted quantal response test for comparing tumour incidence rates

Summary.  The paper presents a case-study of skin fibromas among male rats in the 2-year cancer bioassay of methyleugenol that was conducted by the US National Toxicology Program (NTP). In animal carcinogenicity experiments such as this one, tumour rates are often compared with the Cochran–Armitage (CA) trend test. The operating characteristics of the CA test, however, can be adversely affected by survival differences across groups and by the assumed dose metric. Survival-adjusted generalizations of the CA test have been proposed, but they are still sensitive to the choice of scores that are assigned to the dose groups. We present an alternative test, which outperforms the survival-adjusted CA test which is currently used by the NTP to compare incidence rates. Simulated data from a wide range of realistic situations show that the operating characteristics of the test proposed are superior to those of the NTP's survival-adjusted CA test, especially for rare tumours and wide logarithmic spacings of the dose metric.     

INFERENCE IN DIRICHLET PROCESS MIXED GENERALIZED LINEAR MODELS BY USING MONTE CARLO EM

Generalized linear mixed models are widely used for describing overdispersed and correlated data. Such data arise frequently in studies involving clustered and hierarchical designs. A more flexible class of models has been developed here through the Dirichlet process mixture. An additional advantage of using such mixture models is that the observations can be grouped together on the basis of the overdispersion present in the data. This paper proposes a partial empirical Bayes method for estimating all the model parameters by adopting a version of the EM algorithm. An augmented model that helps to implement an efficient Gibbs sampling scheme, under the non‐conjugate Dirichlet process generalized linear model, generates observations from the conditional predictive distribution of unobserved random effects and provides an estimate of the average number of mixing components in the Dirichlet process mixture. A simulation study has been carried out to demonstrate the consistency of the proposed method. The approach is also applied to a study on outdoor bacteria concentration in the air and to data from 14 retrospective lung‐cancer studies.     

Community mentors as coaches: transforming gender norms through cricket among adolescent males in urban India

Addressing violence against women and girls (VAWG) through the medium of male team sport may be a promising strategy for addressing interpersonal violence and gender norms transformation in urban communities. Parivartan is a violence prevention programme in a large slum community in Mumbai, India, which works with men and boys to reduce violence and promote gender-equitable attitudes and beliefs via membership of a cricket team and mentoring from coaches. This article discusses findings from a recent evaluation of the programme.     

Antecedents of Innovativeness in Technology‐Based Services (TBS): Peering into the Black Box of Entrepreneurial Orientation

Innovativeness is the organization's capability for developing and introducing innovations. We argue that new combinations and recombinations of prior and new knowledge (by way of creating, assembling, and transforming knowledge) result in innovativeness in an organization. We further assert that a knowledge‐based focus on innovativeness is particularly important for firms that are technology‐based. The majority of studies focusing on innovativeness are in the entrepreneurship arena, and a large number of studies consider innovativeness as one of three dimensions of the entrepreneurial orientation (EO) construct, the other two dimensions being proactiveness and risk‐taking. However, recent research has suggested peering into the black box of EO by disaggregating the EO construct and examining the interrelationships among its three components. Hence, using the knowledge‐based view and drawing from multiple disciplines, our study conceptualizes innovativeness as a criterion variable and investigates the antecedent role of proactiveness and risk‐taking propensity on innovativeness in the context of technology‐based services (TBS). We hypothesize that both proactiveness and risk‐taking propensity exhibit a curvilinear relationship with innovativeness and introduce organizational structure formality as a moderator to further explicate these relationships. Our results show that proactiveness has a curvilinear (inverted U relationship) with innovativeness, and that this relationship is attenuated by organizational structure formality. Additional analysis indicates that in TBS firms, risk‐taking propensity has a positive linear relationship with innovativeness, and this relationship is accentuated by organizational structure formality. Finally, we discuss important conceptual and practical implications of our study and provide suggestions for future research.