Mixture of latent trait analyzers for model-based clustering of categorical data

Model-based clustering methods for continuous data are well established and commonly used in a wide range of applications. However, model-based clustering methods for categorical data are less standard. Latent class analysis is a commonly used method for model-based clustering of binary data and/or categorical data, but due to an assumed local independence structure there may not be a correspondence between the estimated latent classes and groups in the population of interest. The mixture of latent trait analyzers model extends latent class analysis by assuming a model for the categorical response variables that depends on both a categorical latent class and a continuous latent trait variable; the discrete latent class accommodates group structure and the continuous latent trait accommodates dependence within these groups. Fitting the mixture of latent trait analyzers model is potentially difficult because the likelihood function involves an integral that cannot be evaluated analytically. We develop a variational approach for fitting the mixture of latent trait models and this provides an efficient model fitting strategy. The mixture of latent trait analyzers model is demonstrated on the analysis of data from the National Long Term Care Survey (NLTCS) and voting in the U.S. Congress. The model is shown to yield intuitive clustering results and it gives a much better fit than either latent class analysis or latent trait analysis alone.     

Charting the Emergence of National Identity in Children in Wales

This multimodal study, set in Wales, demonstrates that children aged nine and ten can clearly define and rationalise their own national identity. It contributes to age related discussions on how children categorise themselves in terms of national identity and the rationale for their choices. The children in the study used single and multiple definitions of national identity and illustrate the increasing plural nature of 21st century Wales. Family, birthplace and residency were identified as factors in shaping their national identity, more so than language, despite the current bilingual policy drive in Wales.     

The Caliban Codex: mud,blood and spurious issues

The internationally known and respected Cherokee Indian artist Jimmie Durham created the conceptual mixed-media installation The Caliban Codex in anticipation of the 1992 quincentennial Columbian celebrations that were held throughout the Americas. He used Shakespeare's The Tempest as a vehicle by which to critique colonialism's appropriation of language and its power to assert colonial authority. He also addressed physiognomy as it was employed during the nineteenth century in a pseudo-scientific endeavour to ‘prove’ the biological legitimacy of racism. In each case Durham employed the methods of mimicry and mockery to address the ambivalent relationship between the coloniser and the colonised as it continues to be experienced.     

A Qualitative Analysis of College Women's Leaving Processes in Abusive Relationships

Abstract

Objective: This study assessed the process of leaving an abusive dating relationship utilizing a qualitative design. Methods: Participants included 123 college women in abusive dating relationships who participated at the beginning and end of a 10-week academic quarter. Results: Qualitative content analyses were used to analyze the transcribed responses to an open-ended question about women's leaving processes over the interim period. A variety of categories and themes emerged for women in different stages of the leaving process, consistent with the Transtheoretical Model of Change and Investment Model. Data also underscored women's lack of acknowledgment, minimization, and normalization of abuse. Conclusions: These data demonstrate the importance of dating violence intervention and prevention programming on college campuses and offer information that may be useful to college health providers who assist women in abusive dating relationships.     

Associations among Maternal Behavior,Delay of Gratification,and School Readiness across the Early Childhood Years

This study examined the developmental pathways from maternal behavior to school readiness within a sample of 1007 children, with a specific focus on the mediating role of delay of gratification (DoG). Maternal behavior across the first 36 months of age was explored as a predictor of children's DoG at 54 months as well as their behavioral and academic competence in kindergarten. Results support sensitivity as a predictor of children's DoG and indicate significant associations between DoG and teacher‐reported externalizing behavior, social skills, and academic skills. Moreover, DoG partially mediated the associations between maternal sensitivity and school readiness skills, with the highest percentage of mediation reported for social skills. Findings indicate maternal sensitivity and DoG as potential targets for efforts aimed at enhancing school readiness among young children.     

Technology transfer concerns of college graduates with disabilities: Profiles in transition from higher education to competitive careers

The article describes the technology transfer concerns reported by a small sample (N=14) of recent college graduates with disabilities. In structured, in-depth interviews, researchers asked respondents to reflect on the extent to which they had utilized technology resources during their college years in preparation for the world of work. Results suggest that colleges and universities need to play a more active role in introducing students with disabilities to both generalized and assistive technology services.