A Stochastic Volatility Model With Markov Switching

This article presents a new way of modeling time-varying volatility. We generalize the usual stochastic volatility models to encompass regime-switching properties. The unobserved state variables are governed by a first-order Markov process. Bayesian estimators are constructed by Gibbs sampling. High-, medium- and low-volatility states are identified for the Standard and Poor's 500 weekly return data. Persistence in volatility is explained by the persistence in the low- and the medium-volatility states. The high-volatility regime is able to capture the 1987 crash and overlap considerably with four U.S. economic recession periods.     

Modelling and estimating heavy-tailed non-homogeneous correlated queues: Pareto-inverse gamma HGLM with covariates

Evidence of communication traffic complexity reveals correlation in a within-queue and heterogeneity among queues. We show how a random-effect model can be used to accommodate these kinds of phenomena. We apply a Pareto distribution for arrival (service) time of individual queue for given arrival (service) rate. For modelling potential correlation in arrival (service) times within a queue and heterogeneity of the arrival (service) rates among queues, we use an inverse gamma distribution. This modelling approach is then applied to the cache access log data processed through an Internet server. We believe that our approach is potentially useful in the area of network resource management.     

Full-Text Aggregator Database Vendors and Journal Publishers: A Study of a Complex Relationship

Abstract

To acquire journal content rights for full-text aggregator databases, database vendors must enter into negotiations and sign contractual agreements with journal publishers. Through a survey, librarians at the University of Colorado at Colorado Springs examined vendors and publishers relationships and the impact of those relationships on full-text journal content in aggregator services.     

Impact on Parents of Receiving Individualized Feedback of Psychological Testing Conducted with Children as Part of a Research Study

While many researchers accept the principle that participants have a right to receive information learned from their participation in research, there are few studies examining the impact of receiving results on participants. This study was developed to examine the impact on parents of the receipt of individual results of research-based psychological testing of their children. A summary of the child's individual results of standardized measures of language and development was sent by mail with the questionnaire designed to assess the impact of receiving results. Response rate from the mailed questionnaire was 55.6% (n?=?74/133). Most parents reported the results as helpful and positive. The majority would receive results again. Overall, the sharing of individualized feedback from psychological testing conducted as part of a research study was well accepted by parents. This practice appears ethically permissible with appropriate support options for addressing participant concerns upon receiving the results as well options for clinical follow-up for the child.     

Calibrated Ambitions: Low Educational Ambition as a Form of Strategic Adaptation Among Chinese Youth in Spain

Deemed “model minorities,” second‐generation Chinese‐Americans have, on average, high levels of educational attainment and, as a result, they have experienced more upward mobility than other groups. Yet, on the other side of the Atlantic, a strikingly different story about Chinese immigrants and their offspring emerges. Based on analysis of the Longitudinal Study of the Second Generation in Spain, findings from this study show that Chinese youths in Spain have substantially lower educational ambitions and attainment than youths from every other nationality. Met with discrimination at school and in the labor market, yet finding financial success in niche markets as small business owners, I argue that the Chinese in Spain have, at least temporarily, forged an alternative pathway of mobility based on entrepreneurial endeavors rather than educational accomplishments – a formula passed on from immigrant parents to their offspring. The way Chinese youths in Spain have calibrated their ambition represents a form of strategic adaptation to the barriers put up against immigrant minorities in Spanish society.     

Comparing the effectiveness of I-BMS-informed self-help interventions in alleviating psychosocial distress for women awaiting the outcome of IVF treatment

Women undergoing in vitro fertilisation experience enormous emotional distress while waiting to find out if they are pregnant; yet their intention to seek help remains low. Interventions that can be easily self-administered may provide a promising alternative. This randomised trial compares psychosocial outcomes of 207 women who received a self-help education booklet containing either spiritually reflective exercise and relaxation techniques, spiritually reflective exercises only, or information about body-mind wellness. Results suggest that knowledge on body-mind wellness protected the women from deteriorating in a range of psychosocial well-being domains that would otherwise have occurred during the waiting period prior to the pregnancy test.     

Review of Chinese sex attitudes and applicability of sex therapy for chinese couples with sexual dysfunction

Although sex therapy techniques have widely been used to help Western couples with sexual dysfunction, there has been little research on the applicability of these techniques among Chinese couples. This article discusses the Chinese views and concepts of sex and sexual dysfunction in the past and present, culturally bound sexual problems, and gender role stereotypes. We suggest that with careful integration of the therapeutic techniques with Chinese sex concepts, sex therapy can be applied to Chinese Couples experiencing problems in sexual functioning.     

Optimal experimental plan for multi-level stress testing with Weibull regression under progressive Type-II extremal censoring

In the design of constant-stress life-testing experiments, the optimal allocation in a multi-level stress test with Type-I or Type-II censoring based on the Weibull regression model has been studied in the literature. Conventional Type-I and Type-II censoring schemes restrict our ability to observe extreme failures in the experiment and these extreme failures are important in the estimation of upper quantiles and understanding of the tail behaviors of the lifetime distribution. For this reason, we propose the use of progressive extremal censoring at each stress level, whereas the conventional Type-II censoring is a special case. The proposed experimental scheme allows some extreme failures to be observed. The maximum likelihood estimators of the model parameters, the Fisher information, and asymptotic variance–covariance matrices of the maximum likelihood estimates are derived. We consider the optimal experimental planning problem by looking at four different optimality criteria. To avoid the computational burden in searching for the optimal allocation, a simple search procedure is suggested. Optimal allocation of units for two- and four-stress-level situations is determined numerically. The asymptotic Fisher information matrix and the asymptotic optimal allocation problem are also studied and the results are compared with optimal allocations with specified sample sizes. Finally, conclusions and some practical recommendations are provided.     

A comparative study of tests for paired lifetime data

In this paper, we investigate different procedures for testing the equality of two mean survival times in paired lifetime studies. We consider Owen’s M-test and Q-test, a likelihood ratio test, the paired t-test, the Wilcoxon signed rank test and a permutation test based on log-transformed survival times in the comparative study. We also consider the paired t-test, the Wilcoxon signed rank test and a permutation test based on original survival times for the sake of comparison. The size and power characteristics of these tests are studied by means of Monte Carlo simulations under a frailty Weibull model. For less skewed marginal distributions, the Wilcoxon signed rank test based on original survival times is found to be desirable. Otherwise, the M-test and the likelihood ratio test are the best choices in terms of power. In general, one can choose a test procedure based on information about the correlation between the two survival times and the skewness of the marginal survival distributions.     

Ethnic and National Sense of Belonging in Canadian Society

There has been long-standing debate among Western nations regarding the best approaches for the integration of immigrants into host societies. The core of this debate is between the proponents of assimilation and multiculturalism. Using a large sample of Canadians, we investigated the link between their sense of belonging to their ethno-racial heritage (ethnic belonging) and to Canada (national belonging) in order to seek answers to the question of whether multiculturalism policies work to strengthen or weaken residents’ loyalty to the nation. Our analyses showed that increases in ethnic belonging significantly predicted increases in national belonging, both for ethno-racial minorities and Whites, after controlling for demographic variables. These findings extend our understanding of acculturation and integration, provide empirical support for multiculturalism, and suggest that active support of immigrant and non-immigrant individuals in maintaining connections to their ethno-racial heritage increases individuals’ loyalty to the nation.