Clustering objects on subsets of attributes (with discussion)

Summary.  A new procedure is proposed for clustering attribute value data. When used in conjunction with conventional distance-based clustering algorithms this procedure encourages those algorithms to detect automatically subgroups of objects that preferentially cluster on subsets of the attribute variables rather than on all of them simultaneously. The relevant attribute subsets for each individual cluster can be different and partially (or completely) overlap with those of other clusters. Enhancements for increasing sensitivity for detecting especially low cardinality groups clustering on a small subset of variables are discussed. Applications in different domains, including gene expression arrays, are presented.     

Prenatal Cardiac Function and Postnatal Cognitive Development: An Exploratory Study

Fetal cardiac function was measured at 24, 30, and 36 weeks gestation and quantified in terms of heart rate, variability, and episodic accelerations. Children's representational capacity was evaluated at 27 months in terms of language and play. Thirty‐ and 36‐wcek‐old fetuses that displayed greater heart‐rate variability and more episodic accelerations, and fetuses that exhibited a more precipitous increase in heart‐rate variability and acceleration over gestation achieved higher levels of language competence. Thirty‐six‐week‐old fetuses with higher heart‐rate variability and accelerations, and steeper growth trajectories over gestation, achieved higher levels of symbolic play. Cardiac patterning during gestation may reflect an underlying neural substrate that persists through early childhood: Individual variation in rate of development could be stable, or efficient cardiac function could positively influence the underlying neural substrate to enhance cognitive performance.     

Profiles of behavioral problems in children who witness domestic violence

Unlike previous investigations of shelter-based samples, our study examined whether profiles of adjustment problems occurred in a community-program-based sample of 175 school-aged children exposed to domestic violence. Cluster analysis revealed three stable profiles/clusters. The largest cluster (69%) consisted of children below clinical thresholds for any internalizing or externalizing problem. Children in the next largest cluster (18%) were characterized as having externalizing problems with or without internalizing problems. The smallest cluster (13%) consisted of children with internalizing problems only. Comparison across demographic and violence characteristics revealed that the profiles differed by child gender, mother's education, child's lifetime exposure to violence, and aspects of the event precipitating contact with the community program. Clinical and future research implications of study findings are discussed.     

Measuring changes in interagency collaboration: an examination of the Bridgeport Safe Start Initiative

This paper describes the evaluation of interagency collaboration in a network of child-serving providers as part of the evaluation of the Bridgeport Safe Start Initiative (BSSI). In line with the system of care approach, the objectives of BSSI included reducing fragmentation of efforts and delivering integrated services to families of young children exposed to or at risk of exposure to family violence. Interagency collaboration was examined via social network and focus group data collected at three time points starting at baseline. Network analysis findings suggest that over time the network structure became consistent with BSSI's vision of an ideal collaborative network structure. Focus group findings, however, present a more complex picture of the status of collaboration. This paper sheds light on approaches and challenges to measuring interagency collaboration in a service delivery system and communicating social network analysis findings to stakeholders in a way that is accessible and useful.     

Amateur craft‐artists: Marginal leisure roles in a marginal art world (1)

Amateurism is an important but marginal leisure role, in which the boundaries between work and leisure are blurred. This phenomenon has been studied by Stebbins as a subjective social reality. His conceptualization of amateurism was used as a model in the examination of survey data on craft‐artists and it was found to apply rather well to the analysis of quantitative data. As a self‐identified category of craft‐artists, amateurs were statistically marginal between professionals and dabblers.     

Inclusion of children with disabilities in mainstream child development research

This study investigated whether children with disabilities are excluded from mainstream child development research. Fifteen per cent of 533 articles from Child Development and Developmental Psychology (1996–2010) were randomly selected. The exclusion rate was 89.9% when no mention of participants with disabilities was interpreted as exclusion and 66.7% when only studies mentioning disabilities were surveyed; 74% of studies did not provide justification for exclusion. Most studies could have included children with disabilities. Inclusion could be increased by adopting universal design principles and accommodations so that more children with disabilities can gain equal access to research opportunities and the benefits that accrue.     

Student Self‐Reported Positive Purpose Over Two Years in Urban Middle Schools

We used Developmental Systems Theory as a framework for understanding the role of contextual factors in the development of purpose in urban adolescents. The sample included primarily low‐socioeconomic students of color attending urban middle schools (n = 2,629; 10–16 years of age). Longitudinal data were collected at four time points across two years. We used hierarchical linear modeling to model change in purpose. On average, purpose declined over time. We also identified several predictors of intercept and slope. For example, Black youth had a higher average purpose intercept, as well as a steeper average decline than other racial/ethnic groups. Females demonstrated a higher average purpose intercept than males, but this effect disappeared when academic achievement was added to the model.