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.     

损失模拟模型的模拟与检验

为帮助精算师在不同的数据环境下选择最优的准备金评估方法,美国非寿险精算师协会组织开发了一个产生模拟索赔数据的开源软件系统——损失模拟模型,然而损失模拟模型是否能够按指定参数要求产生模拟数据需要进行检验.文章采用不同的参数估计方法和拟合优度检验方法对模拟索赔次数的分布、索赔额的趋势以及不同险种索赔次数之间的相关结构进行了统计检验,结果表明损失模拟模型对索赔次数的分布、索赔额的趋势能够产生一致的模拟,而对索赔次数数据之间相关结构的模拟存在不稳定性.     

Very Preterm and Full‐Term Infants’ Response to Socio‐Emotional Stress: The Role of Postnatal Maternal Bonding

Very preterm (VPT) infants are at risk for altered socio‐emotional stress regulation, even in the absence of perinatal complications. Moreover, becoming a mother of a VPT infant is a traumatic event, which might affect the establishment of a bonding relationship toward the infant during the postnatal period. The main aim of the present study was to assess the association between maternal postnatal bonding and socio‐emotional stress response in 3‐month‐old VPT infants, compared to full‐term (FT) controls. Thirty‐three VPT and 28 FT infant‐mother dyads underwent the maternal Face‐to‐Face Still‐Face (FFSF) procedure to assess socio‐emotional stress regulation. Maternal postnatal bonding was measured through the Maternal Post‐Natal Attachment Scale (MPAS), which includes three scales: Quality of attachment, Absence of hostility, and Pleasure in interaction. The VPT infants exhibited less self‐directed and other‐directed regulatory behaviors during the Still‐Face episode. Mothers of VPT infants reported lower Quality of attachment compared to FT counterparts. Importantly, higher levels of Quality of attachment were associated with more other‐directed behaviors during the Still‐Face episode in FT dyads, whereas this was not observed in VPT dyads. In conclusion, VPT infants might be exposed to a double‐risk condition for socio‐emotional development, encompassing both difficulties in stress response and the exposure to a less‐than‐optimal maternal bonding.     

Self‐Esteem,the Fear of Crime,and the Decision to Protect Oneself From Victimization

This research extends prior work that examines self‐esteem as an outcome of protective behaviors against crime victimization by focusing instead on the moderating influence of self‐esteem on the relationship between the fear of crime and the decision to protect oneself from victimization. The fear of crime is conceptualized as two separate components (fear of victimization and perceived risk) in accordance with prior work. Self‐esteem is conceptualized as three separate components (worth, efficacy, and authenticity), and measured with a recently designed instrument for capturing each aspect of self‐esteem separately. Data are collected through surveys of a population at high risk for victimization (undergraduate college students). Logistic regression analyses demonstrate that self‐esteem does play a role for deciding whether to engage in protective behaviors, and that the specific components of self‐esteem moderate defensive behavioral outcomes differently. Specifically, the self‐worth, self‐efficacy, and authenticity components of self‐esteem influence the decision to carry protection, but not the decision to take a self‐defense class. Implications for both the fear of crime and self‐esteem literatures are addressed.     

Unanticipated ethical issues in a participatory research project with individuals with intellectual disability

The conduct of a participatory research investigation into the everyday literacy of adults with intellectual disability within the context of a PhD thesis highlighted issues related to the ethics of participatory research and the need to revisit and reconsider ethical guidelines around working with individuals with intellectual disability. Tensions were identified between participatory research ideology and the reality of research experiences, with additional issues arising due to disability in the first author.     

Usability in product design--the importance and need for systematic assessment models in product development--Usa-Design Model (U-D) ©

In product design, human factors are considered as an element of differentiation given that today's consumer demands are increasing. Safety, wellbeing, satisfaction, health, effectiveness, efficiency, and other aspects must be effectively incorporated into the product development process. This work proposes a usability assessment model that can be incorporated as an assessment tool. The methodological approach is settled in two stages. First a literature review focus specifically on usability and developing user-centred products. After this, a model of usability named Usa-Design (U-D?) is presented. Consisted of four phases: understanding the use context, pre-preliminary usability assessment (efficiency/effectiveness/satisfaction); assessment of usability principles and results, U-D? features are modular and flexible, allowing principles used in Phase 3 to be changed according to the needs and scenario of each situation. With qualitative/quantitative measurement scales of easy understanding and application, the model results are viable and applicable throughout all the product development process.     

… Do as the Romans do. A model of conformity with the endogenous formation of preferences

This note is an answer to a previous model on conformity in public goods contributions developed by Carpenter (2004), where a population evolution is allowed according to the standard replicator dynamic (Taylor and Jonker, 1978, Maynard Smith, 1982). To confirm his theoretical prediction, Carpenter developed an experiment showing that free riding actually grows faster when agents have the information necessary to conform. The model and the experiment are, however, inherently different, for the time scales of the model are not able to capture the short run convergence of behavior in the experimental laboratory.We here present a model of conformity which offers the same laboratory results as Carpenter without resorting to evolutionary models, and also gives agents the chance to adopt different strategies implying various levels of cooperation.     

Extending and Expanding Parenthood: Parental Support to Young Adult Children

Today’s transition to adulthood in the United States is complex and drawn out. Current economic and social conditions favor young workers who have completed post‐secondary education, resulting in many young adults delaying exiting the family home, marriage, and parenthood. The role of parental support (both affective and instrumental) in navigating this period of development is becoming increasingly important and plays a substantial role in reproducing inequality across generations. Informed by the life course perspective, this review provides readers with a basic understanding of what types of support parents provide, when it is expected and received, and finally, how it is related to attainment and the quality of the parent–child relationship throughout young adulthood. We conclude with a discussion of how class differences in intergenerational support intersect with institutional factors to enhance the reproduction of inequality and how the new demands for parental support throughout young adulthood is more than many families can provide.     

Is Household Wealth Sustainable? An Examination of Asset Poverty Reentry After an Exit

This paper analyzed the influence of financial behaviors on the duration out of asset poverty while controlling for households’ life cycle and demographic characteristics. We found evidence for the existence of structural barriers to asset acquisition. Asset accumulation at or above levels equal to nine-months worth of income at the income-poverty level was important for improving a household’s odds of permanently escaping asset poverty, but a linear relationship between asset accumulation and the likelihood of returning to asset poverty did not emerge. Moreover, minimizing debt and diversifying the asset portfolio to include more productive assets were positively related to maintaining assets; but households should also consider the risks associated with portfolio allocations.