Flexible mixture modeling via the multivariate t distribution with?the?Box-Cox transformation: an?alternative to?the?skew-t distribution

Cluster analysis is the automated search for groups of homogeneous observations in a data set. A popular modeling approach for clustering is based on finite normal mixture models, which assume that each cluster is modeled as a multivariate normal distribution. However, the normality assumption that each component is symmetric is often unrealistic. Furthermore, normal mixture models are not robust against outliers; they often require extra components for modeling outliers and/or give a poor representation of the data. To address these issues, we propose a new class of distributions, multivariate t distributions with the Box-Cox transformation, for mixture modeling. This class of distributions generalizes the normal distribution with the more heavy-tailed t distribution, and introduces skewness via the Box-Cox transformation. As a result, this provides a unified framework to simultaneously handle outlier identification and data transformation, two interrelated issues. We describe an Expectation-Maximization algorithm for parameter estimation along with transformation selection. We demonstrate the proposed methodology with three real data sets and simulation studies. Compared with a wealth of approaches including the skew-t mixture model, the proposed t mixture model with the Box-Cox transformation performs favorably in terms of accuracy in the assignment of observations, robustness against model misspecification, and selection of the number of components.     

The Effects of Children, Dual Earner Status, Sex Role Traditionalism, and Marital Structure on Marital Happiness Over Time

In this study, the link between marital happiness and the advent of children is demonstrated, accounting for dual earner status, sex role traditionalism, and marital structure. A subset of 1,275 respondents from a longitudinal data set (Marital Instability Over the Life Course: A Three Wave Panel Study, 1980–1988) whom remained married through the 3 waves was used to compare the level of marital happiness of respondents who added children between waves to those who did not. Although the addition of children negatively affected marital structure and thus indirectly lowered marital happiness, results showed children also had positive counterbalancing direct effects. Dual-earner status, income, and sex role nontraditionalism were shown to mitigate the negative effects of children on marital happiness.     

COMPARISON OF THREE NON-PARAMETRIC TESTS FOR BIVARIATE INTERCHANGEABILITY1

Given a random sample(X₁, Y₁), …,(X_n, Y_n) from a bivariate (BV) absolutely continuous c.d.f. H (x, y), we consider rank tests for the null hypothesis of interchangeability H₀: H(x, y). Three linear rank test statistics, Wilcoxon (W_N), sum of squared ranks (SSR_N) and Savage (S_N), are described in Section 1. In Section 2, asymptotic relative efficiency (ARE) comparisons of the three types of tests are made for Morgenstern (Plackett, 1965) and Moran (1969)BV alternatives with marginal distributions satisfying G(x) = F(x/θ) for some θ≠ 1. Both gamma and lognormal marginal distributions are used.     

Explaining Restrictive TANF Policies: Group Threat Hypothesis and State Economy Conditions

ABSTRACT

This study examined whether TANF policies' restrictiveness is related to states' racial composition and economic conditions. The data were extracted from various reports dated 2000–2014. Results from generalized least squares random-effects modeling showed the number of restrictive TANF policies to be associated positively with larger populations of Hispanic individuals and associated negatively with larger populations of African American individuals. No association was found between policies' restrictiveness and “other” minority population, nor between restrictiveness and either poverty or unemployment. One conclusion suggested by the analysis is that restrictive TANF policies result from dramatic increases in the Hispanic population that trigger the dominant group's resentment of ethnic minorities. Several policy implications are stated.     

Client Improvement and Working Alliance: Case-Manager Factors

ABSTRACT

To investigate working alliance and other factors in case managers' perceptions of client improvement, data were collected from 95 case manager–adult client pairs from community-based agencies. Per the multiple regression results, client improvement as perceived by case manager increased with level of working alliance as perceived by case manager, and with manager age and social work education at the bachelor's level and master's level. Such improvement decreased with level of client substance abuse as perceived by manager. No association was found between client improvement as perceived by case manager and four further tested factors: level of working alliance as perceived by client; homogeneous gender and ethnicity of client and case manager; case manager work experience; duration of client working with the current case manager. Implications for practice and education are discussed.     

Unaffordable healthcare amid phenomenal growth: the case of healthcare protection in reform China

This article provides an up-to-date assessment of China's reformed urban healthcare system. It illustrates that, in the Chinese case, economic growth does not automatically bring equitable healthcare protection; policy and system designs are also important. The article finds that the reformed urban healthcare system is financially sustainable, but that individual citizens contribute the largest share of healthcare costs, whilst the state is reducing its financial commitment. It also reports the views of two principal stakeholder groups. The survey findings indicate the endorsement of an old ethos for a strong state in healthcare protection. But a substantial minority view is also unveiled, which supports access to healthcare on the basis of insurance contributions. In sum, affordability remains a critical issue for the Chinese despite the fact that they have a new healthcare system and a strong economy.     

Exploring school ethos: an investigation of children’s human rights in two secondary institutions in Hong Kong

From 2009 to 2011, the authors launched the Basic Law Education Project: Education for Human Rights and the Rule of Law in Hong Kong. This article focuses on a subset of the overarching data-set and discusses the findings that resulted from a comparative analysis of two participating schools. A survey was deployed to assess the extent to which a human rights friendly ethos existed in several institutions. Randomly selected students and all teachers from both schools were invited to participate. The collected data revealed noteworthy trends in mean scores between teachers and students in areas such as equal and fair treatment; protection of and appeal for rights; and feelings of being loved, respected, and blessed. School mission and leadership style appeared to account for significant differences. Additionally, we offer recommendations for practices that may improve human rights ethos in schools.     

Racial Attitudes in the Deep South: Persistence and Change at the University of Alabama, 1963–2013*

Using data from a unique series of surveys collected between 1963 and 2013, this study examines racial attitudes among young white adults in the Deep South over a 50-year period. Repeated surveys of University of Alabama students in 1963, 1966, 1969, 1972, 1983, 1988, and 2013 measured racial stereotypes, support for racial segregation, and in the 2013 study, racial resentment and support for ameliorative racial policies. Analyses show that in the 1960s endorsement of racial stereotypes was a powerful predictor of support for racial segregation. By the early 1970s, racial integration became a reality in the Deep South and, paralleling broad trends in U.S. society, endorsement of racial stereotypes and support for racial segregation declined. Simultaneously, threats to whites' position in the form of ameliorative racial policies (including affirmative action) emerged along with racial resentment. By 2013, racial resentment, rather than racial stereotyping, was the primary determinant of white students' opposition to racial change. Our findings support Herbert Blumer's (1958) argument that racial prejudice exists in a sense of group position, and that it functions to preserve the advantaged position of the dominant group regardless of changes in the form that prejudice takes.