A generalized bivariate Bernoulli model with covariate dependence

Dependence in outcome variables may pose formidable difficulty in analyzing data in longitudinal studies. In the past, most of the studies made attempts to address this problem using the marginal models. However, using the marginal models alone, it is difficult to specify the measures of dependence in outcomes due to association between outcomes as well as between outcomes and explanatory variables. In this paper, a generalized approach is demonstrated using both the conditional and marginal models. This model uses link functions to test for dependence in outcome variables. The estimation and test procedures are illustrated with an application to the mobility index data from the Health and Retirement Survey and also simulations are performed for correlated binary data generated from the bivariate Bernoulli distributions. The results indicate the usefulness of the proposed method.     

Systemic Uptake and Clearance of Chloroform by Hairless Rats Following Dermal Exposure. I. Brief Exposure to Aqueous Solutions

The systemic uptake of chloroform from dilute aqueous solutions into live hairless rats under conditions simulating dermal environmental exposure was studied. Whole blood was sampled during a 30-min immersion of an animal within water containing a known concentration of chloroform and then for 5.5 h following its removal from the bath. The amount of chloroform systemically absorbed was determined by comparing the AUCs of the blood concentration vs. time plots from dermal exposure to that obtained after IV infusion (for a period of 30 min) of an aqueous solution containing a known amount of chloroform (positive control). Although dermal data implied two-compartment disposition characteristics, IV infusion data fit best to a three-compartment disposition. Linear pharmacokinetics was observed both by IV administration and percutaneous absorption at the dose levels studied. Chloroform was detected in the rat blood as early as 4 min following exposure. Our findings suggest that about 10.2 mg of chloroform was systemically absorbed after dermal exposure of a rat to an aqueous solution of 0.44 mg/ml. This amount is substantially higher than the predictions of mathematical risk-models put forth by some investigators. However, when expressed as the "effective" permeability coefficient ( K _p^eff), close agreement was noticed between our value and those estimated by others using physiologically based pharmacokinetic (PBPK) models. Also, in terms of K _p^eff, reasonable agreement existed between our and another investigator's past estimates of uptake based on depletion of bath level of chloroform and the actual uptake measured in our current experiments. The estimated onset of systemic entry seen here is entirely consistent with our estimate of how long it takes to establish the diffusion gradient across the stratum comeum based on tape stripping.     

Analyzing dependence in incidence of diabetes and heart problem using generalized bivariate geometric models with covariates

For analyzing incidence data on diabetes and health problems, the bivariate geometric probability distribution is a natural choice but remained unexplored largely due to lack of models linking covariates with the probabilities of bivariate incidence of correlated outcomes. In this paper, bivariate geometric models are proposed for two correlated incidence outcomes. The extended generalized linear models are developed to take into account covariate dependence of the bivariate probabilities of correlated incidence outcomes for diabetes and heart diseases for the elderly population. The estimation and test procedures are illustrated using the Health and Retirement Study data. Two models are shown in this paper, one based on conditional-marginal approach and the other one based on the joint probability distribution with an association parameter. The joint model with association parameter appears to be a very good choice for analyzing the covariate dependence of the joint incidence of diabetes and heart diseases. Bootstrapping is performed to measure the accuracy of estimates and the results indicate very small bias.     

Influence of personality traits on Facebook engagement and their effects on socialization behavior and satisfaction with university life

Several factors influence Facebook users’ engagement. This study investigates the correlations between Facebook engagement and users’ personality traits. This study also analyses the impact of Facebook engagement on students’ socialization behavior and their satisfaction with their university life. A dataset of 994 Malaysian students was collected and used for analysis. The outcome of the analysis illustrates that students’ personality traits have a positive influence on Facebook engagement. Subsequently, Facebook engagement was found to have an influence over students’ socialization behavior and their satisfaction with university life. The results can be used by educators as a guide for their curriculum development, i.e., consideration of wider usage of Facebook in conducting courses.     

Identifying the Components of Social Capital by Categorical Principal Component Analysis (CATPCA)

Social Indicators Research - Social capital is a promising concept, widely used by social science researchers in analysing factors that contribute to the persistence of various economic issues....     

Estimation and tests for a longitudinal regression model based on the Markov chain

In this paper, the dependence of transition probabilities on covariates and a test procedure for covariate dependent Markov models are examined. The nonparametric test for the role of waiting time proposed by Jones and Crowley [M. Jones, J. Crowley, Nonparametric tests of the Markov model for survival data Biometrika 79 (3) (1992) 513–522] has been extended here to transitions and reverse transitions. The limitation of the Jones and Crowley method is that it does not take account of other covariates that might have association with the probabilities of transition. A simple test procedure is proposed that can be employed for testing: (i) the significance of association between covariates and transition probabilities, and (ii) the impact of waiting time on the transition probabilities. The procedure is illustrated using panel data on hospitalization of the elderly population in the USA from the Health and Retirement Survey (HRS).     

The Case of the Disappearing Mexican Americans: An Ethnic-Identity Mystery

We examine the issue of identification stability for U.S.-born Mexican Americans, by far the largest of the ethnic groups growing as a result of contemporary immigration. We demonstrate a significant exodus from the group as identified by the census. Although changes in the wording of the census question may have contributed to this loss, a major portion, as revealed by comparisons of birth cohorts across the 1980, 1990, and 2000 Censuses, occurs because individuals who identified themselves as Mexican American at an earlier point in time do not do so at a later point. In addition, there are exits that occur between generations because of past intermarriage, evident in the number of non-Hispanics who claim Mexican ancestry. The losses appear to be accounted for by two kinds of identity shifts: toward identities that have a mainstream character and thus appear reflect conventional assimilation; and toward identities that have a pan-ethnic character, i.e., with Hispanics or Latinos. These exits are selective, but in complex and partially off-setting ways. Nevertheless, the comparison of the characteristics of U.S.-born members of the Mexican–American group over time is likely to be affected by changing patterns of identification.

Convention on the Elimination of Discrimination Against Women and the Prospect of Development of Muslim Personal Law in Singapore

This paper examines Singapore's partial reservations to Articles 2 and 16 of the United Nations Convention on the Elimination of Discrimination against Women (CEDAW). It contends that the reservations justified on the basis of protecting the rights of the Muslim minority community to practice its personal law has unwittingly impeded the potential of reviewing and addressing significant gaps and limitations in the ways in which the laws are conceived and administered. More pertinently, the policy reinforces the dominance of traditionalism in the thinking of dominant stakeholders of the law. Taking the standpoint that the values of equality and non-discrimination on the basis of gender espoused by CEDAW are compatible with the objectives of Muslim law, this paper maintains that ratifying the relevant Articles of CEDAW will strengthen the process of the development of the Muslim personal law and address essentialist presumptions of the law. This perspective departs from the dominant discourse on the Muslim law and CEDAW which is framed in terms of conflict and polarity between the law and human rights, religious law and women's rights, and universal values versus cultural relativism.     

Examining family and school factors as predictors of delinquency: A study of juvenile offenders,at‐risk students,and low‐risk students in Malaysia

This study aims to examine family and school factors as predictors of delinquency among adolescents in Malaysia. A total of 101 juvenile offenders, 86 at‐risk students, and 92 low‐risk students were involved in this study. Multinomial logistic regression was used to predict the likelihood of an adolescent being in a group of juvenile offenders or of being an at‐risk or low‐risk student, based on four predictor variables: family structure, family relationships, school relationships, and commitment to learning. The results show that family relations, school relations, and commitment to learning have different predictive effects on the likelihood of different levels of delinquent behavior. However, family structure is not found to be a significant predictor in the logistic regression in this study. The findings of the study suggest that keeping young people in school can serve as a strong protective factor that serves to prevent at‐risk students from moving along the trajectory of serious delinquent behaviors.     

Labour Market and Human Capital Behaviour of Immigrant Couples: Evidence from Australia

We examine the labour market and human capital investment behaviour of immigrant couples in Australia. The family investment hypothesis (FIH) states that immigrant husbands, whom the FIH assumes to be the primary earners in the family, will invest more in their human capital than immigrant wives, whom the FIH assumes to be secondary earners. Using longitudinal data from Household, Income and Labour Dynamics in Australia (HILDA) for the period 2001 to 2014, we do not find support for the FIH. Instead, we find that foreign-born husbands and wives share similar labour market assimilation patterns with respect to hours of work and wages. Our estimates suggest that immigrant wives' labour market behaviour can be better explained by their own long-term career progression and labour market assimilation, than through supporting their husbands' labour market assimilation.