Testing homogeneity in semiparametric mixture case–control models

Parametric and semiparametric mixture models have been widely used in applications from many areas, and it is often of interest to test the homogeneity in these models. However, hypothesis testing is non standard due to the fact that several regularity conditions do not hold under the null hypothesis. We consider a semiparametric mixture case–control model, in the sense that the density ratio of two distributions is assumed to be of an exponential form, while the baseline density is unspecified. This model was first considered by Qin and Liang (2011 Qin, J., Liang, K.Y. (2011). Hypothesis testing in a mixture case–control model. Biometrics 67(1):182–198.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar], biometrics), and they proposed a modified score statistic for testing homogeneity. In this article, we consider alternative testing procedures based on supremum statistics, which could improve power against certain types of alternatives. We demonstrate the connection and comparison among the proposed and existing approaches. In addition, we provide a unified theoretical justification of the supremum test and other existing test statistics from an empirical likelihood perspective. The finite-sample performance of the supremum test statistics was evaluated in simulation studies.     

The Relation of Negative Career Thoughts to Depression and Hopelessness

Although some research literature focuses on the integration of mental health and career counseling, there has been little that examines both areas in relation to depression and hopelessness. This study investigated the relationship among dysfunctional career thinking, depression, and hopelessness in a sample of 139 undergraduate and graduate students seeking drop‐in or individual career counseling services at a university career center. The authors found that two aspects of dysfunctional career thinking, decision‐making confusion and commitment anxiety, accounted for a significant amount of variance in depression. Decision‐making confusion also accounted for a significant amount of variance in hopelessness. Implications for counseling practice include the need for more careful screening of career clients who present with high levels of anxiety and negative thinking. Future research could involve more diverse client populations, such as unemployed adults, and explore the use of additional screening measures to assess the intersection of career and mental health issues.     

TWO-PIECE VON NEUMANN-MORGENSTERN UTILITY FUNCTIONS*

Thirty empirically assessed utility functions on changes in wealth or return on investment were examined for general features and susceptability to fits by linear, power, and exponential functions. Separate fits were made to below-target data and above-target data. The usual “target” was the no-change point. The majority of below-target functions were risk seeking; the majority of above-target functions were risk averse; and the most common composite shape was convex-concave, or risk seeking in losses and risk averse in gains. The least common composite was concave-concave. Below-target utility was generally steeper than above-target utility with a median below-to-above slope ratio of about 4.8. The power and exponential fits were substantially better than the linear fits. Power functions gave the best fits in the majority of convex below-target and concave above-target cases, and exponential functions gave the best fits in the majority of concave below-target and convex above-target cases. Several implications of these results for decision making under risk are mentioned.     

Gay and lesbian partnership: Evidence from California

Much recent research on sexual minorities has used couples-based samples, which--by construction--provide no information on nonpartnered individuals. We present the first systematic empirical analysis of partnership and cohabitation among self-identified gay men and lesbians using two independent, large, population-wwbased data sources from California. These data indicate that 37%-46% of gay men and 51%-62% of lesbians aged 18-59 are in cohabiting partnerships (compared with 62% of heterosexual individuals in coresidential unions at comparable ages). Unlike previous research, we find that white and highly educated gay men and lesbians are more likely to be partnered, and we confirm that same-sex cohabiting partners in our data have demographic characteristics that are similar to California same-sex couples from Census 2000. We also present the first detailed analysis of officially registered domestic partnerships in California. We find that almost half of partnered lesbians are officially registered with the local or state government, while less than a quarter of partnered gay men are officially registered. We conclude with implications of our findings for couples-based research on gay men and lesbians, as well as recommendations for survey data collection.     

Are Father’s or Mother’s Socioeconomic Characteristics More Important Influences on Student Performance? Recent International Evidence

Since the early 1970s the importance of mothers’ socioeconomic characteristics on their children’s educational and occupational attainment has been acknowledged. However, it is not clear if fathers’ characteristics have a stronger influence because men usually have stronger attachments to the labour market, or alternatively mothers’ characteristics are more important because of their greater role in children’s socialization. This study addresses this question by comparing the influence of father’s and mother’s education and occupation on student performance in literacy and numeracy using data from 30 countries. The impact of mother’s education is usually greater or comparable to that of father’s education. In contrast, substantially stronger effects for mother’s occupational status compared to father’s were rare. In most countries the impact of mother’s socioeconomic characteristics (education plus occupation) on student performance is comparable to that for father’s. Of the four indicators of socioeconomic background, father’s occupational status and mother’s educational attainment tend to have stronger effects, although many countries do not conform to this pattern. There are indications that the relative importance of mother’s characteristics have increased over time.

Characterization of Unacceptable Solutions in LP Discriminant Analysis*

Many linear programming models have been proposed for performing discriminant analysis. Partial characterizations for unacceptable solutions have been presented and new models proposed to circumvent these problems. In this paper those conditions leading to unacceptable solutions for all two-group models are characterized.     

Unequal Partners? Local Government Reorganization and the Voluntary Sector

British local government has recently undergone its most far-reaching reorganization for twenty-five years. The impact of this reorganization was considerable within local authorities but it also substantially affected other organizations with which they worked at a local level. This paper explores the perspectives of voluntary sector organizations involved in social care: a set of actors which, prior to reorganization, had been encouraged by central and local government, through notions of partnership and through community care legislation, to undertake more direct roles in service delivery, consultation and strategic planning. During the consultative period prior to reorganization, many voluntary organizations reported that they had been marginal to the process. Reflecting on the process of reorganization itself, many voluntary organization respondents commented that it had been disruptive and provoked considerable anxiety. Post-reorganization, voluntary organizations felt that rebuilding of relationships was necessary and that the promise of partnership had meant little in practice at a time of potential crisis for local.     

Living on the margin: disabled Iranians in Belgian society

This paper explores the antecedents, experiences and consequences of marginalization as reported and dealt with by disabled Iranian immigrants in Belgium. This work extends the work of Gallie and colleagues and Siegrist demonstrating that the forces of marginalization applicable to all immigrants are particularly pertinent to disabled immigrants. The research is based on 26 in‐depth, face‐to‐face interviews, focus groups, interviews with government officials and immigration experts, ethnographic work and official government statistics. The findings detail how the combined forces of history, context and reasons for immigration; isolation, vulnerability and perceived loss of control; religion and rejection; lack of reciprocity in social exchanges; problems in obtaining jobs; and difficulties in negotiating an entry into Belgian society combine to sustain marginizalation. As a consequence, disabled immigrants in this group are generally excluded from society and discriminated against in terms of citizenship, education, jobs and general acceptance.