Can the Web-Form WHOQOL-BREF be an Alternative to the Paper-Form?

The purpose of this study was to test whether the web version is an alternative to the paper version of the short version of the World Health Organization Quality of Life assessment (WHOQOL-BREF). Two studies were conducted. Study 1 used crossover self-controlled trials with 80 participants to compare the web and paper versions and to determine the test–retest reliability of the web version. Study 2 used data from 1,016 web participants to analyze the internal consistency and concurrent and construct validity of the web version. The correlations of domain scores between the web and paper versions ranged from 0.71 to 0.85. Dependent t tests showed no significant differences in domain scores between these two versions. The intra-class correlation coefficients (ICC) for test–retest reliability of web version ranged from 0.79 to 0.91. The Cronbach’s α for internal consistency reliability ranged from 0.60 to 0.83. Multiple regression models indicated that the web version has good concurrent validity. Confirmatory factor analysis (CFA) for the second-order hierarchical factor model also supported the construct validity of the web version. The web version of the WHOQOL-BREF can be the alternative to the paper version for health-related quality of life (HR-QOL) evaluation.     

Chi-Square quantile-based multivariate variance monitoring for individual observations

Under the normality assumption, some statistics for monitoring a multivariate process variance for individual observations can be used to detect a variance shift, but the distribution of their in-control run length has a high variance as well as the median that is extremely smaller than the mean, which leads to many false alarms in the in-control process. In this paper, we propose a chi-square quantile-based monitoring statistic which is free of the problems. The numerical experiments show that the proposed monitoring statistics outperform the existing monitoring statistics in terms of the detection of a shift for the variance.     

The weighted general linear model for longitudinal medical cost data – an application in colorectal cancer

Identifying cost-effective decisions that can take into account of medical cost and health outcome is an important issue under very limited resources. Analyzing medical costs has been challenged owing to skewness of cost distributions, heterogeneity across samples and censoring. When censoring is due to administrative reasons, the total cost might be related to the survival time since longer survivals are likely to be censored and the corresponding total cost will be censored as well. This paper uses the general linear model for the longitudinal data to model the repeated medical cost data and the weighted estimating equation is used to find more accurate estimates for the parameter. Furthermore, the asymptotic properties for the proposed model are discussed. Simulations are used to evaluate the performance of estimators under various scenarios. Finally, the proposed model is implemented on the data extracted from National Health Insurance database for patients with the colorectal cancer.     

Who are People Willing to Date? Ethnic and Gender Patterns in Online Dating

The United States is a rapidly diversifying country with ethnic minorities comprising over a quarter of the US population. By the year 2050, over half of the United States will be ethnic minority, underscoring the importance of better understanding race relations and willingness to date intra- and inter-racially. Data from 2,123 online dating profiles were randomly collected from four racial groups (Asian, Black, Latino, and White). Results indicated that willingness to date intra-racially was generally high and that willingness to date inter-racially was lower and influenced by racial social status. Because men evidenced an overall high willingness to date inter-racially, women’s willingness to out-date provided a more accurate depiction of racial social status and exchange. Women of higher racial status groups were less willing than those from lower status groups to outdate. Results are explored and discussed in relation to different theories of interpersonal attraction and dating.     

The Structural Birnbaum Importance of Consecutive-k Systems

This paper is concerned with three types of structural Birnbaum importance of components in a consecutive-k system. We accomplish the following three tasks:(i) Survey existing results, including pointing out results claimed but proofs are incomplete.(ii) Give some new results and useful lemmas.(iii) Observe what are still provable and what are not with the help of extensive computing.     

Block Bootstrapping for Kernel Density Estimators under ψ-Weak Dependence

Block bootstrap methods are applied to kernel-type density estimator and its derivatives for ψ-weakly dependent processes. Nonparametric density estimation is discussed via moving block bootstrap (MBB) and disjoint block bootstrap (DBB). Asymptotic validity is proved for MBB and DBB. A Monte-Carlo experiment compares confidence intervals based on MBB and DBB with an existing method based on normal approximation (NA) in terms of serial correlation, dynamic asymmetry, and conditional heteroscedasticity. The experiment shows that, in cases of substantial serial correlation, MBB and DBB perform better than NA and, in the other cases, MBB and DBB perform as good as NA.     

Some pitfalls of tests of separate families of hypotheses: normality vs. lognormality

It is often desirable to test non-nested hypotheses. Cox (1961, 1962) proposed forming a log-likelihood ratio from their maxima and then comparing this value to its expected value under the null hypothesis. Pitfalls exists when we apply Cox's test to the special case of testing normality versus lognormality. Pesaran (1981) and Kotz (1973) pointed out the slow convergence rate of the Cox's test. In this paper, this fact has been reemphasized; moreover, we propose an alternative likelihood ratio test which remedies problems arising from negative estimates of the asymptotic variance of Cox's test statistic and is uniformly more powerful than most commonly used tests.     

Some limitation on stein's phenomenon

We show that Stein's phenomenon is impossible for the following decision setting: the parameter space is compact, the loss function is the sum of coordinatewise strictly convex continuous loss functions, and the probability density function having the same support for every parameter θ is continuous in θ. Therefore, any coordinatewise admissible decision rule is admissible.     

An algorithn for generating a basis of the trades on t-designs

For the purpose of constructing t-designs (a special family of incomplete block designs) from a given design, a trade off method has been introduced and studied [Hedayat and Li (1979)]. In this paper, we present a computer algorithm for generating a basis of the trades on t-designs utilizing the results of Graham, Li and Li (1980).