Rank Tests for Clustered Survival Data

In a clinical trial, we may randomize subjects (called clusters) to different treatments (called groups), and make observations from multiple sites (called units) of each subject. In this case, the observations within each subject could be dependent, whereas those from different subjects are independent. If the outcome of interest is the time to an event, we may use the standard rank tests proposed for independent survival data, such as the logrank and Wilcoxon tests, to test the equality of marginal survival distributions, but their standard error should be modified to accommodate the possible intracluster correlation. In this paper we propose a method of calculating the standard error of the rank tests for two-sample clustered survival data. The method is naturally extended to that for K-sample tests under dependence.     

Censored quantile regression for residual lifetimes

We propose a regression method that studies covariate effects on the conditional quantiles of residual lifetimes at a certain followup time point. This can be particularly useful in cancer studies, where more patients survive cancers initially and a patient’s residual life expectancy is used to compare the efficacy of secondary or adjuvant therapies. The new method provides a consistent estimator that often exhibits smaller standard error in real and simulated examples, compared to the existing method of Jung et al. (2009). It also provides a simple empirical likelihood inference method that does not require estimating the covariance matrix of the estimator or resampling. We apply the new method to a breast cancer study (NSABP Protocol B-04, Fisher et al. (2002)) and estimate median residual lifetimes at various followup time points, adjusting for important prognostic factors.     

Relative error prediction via kernel regression smoothers

In this article, we introduce and study local constant and local linear nonparametric regression estimators when it is appropriate to assess performance in terms of mean squared relative error of prediction. We give asymptotic results for both boundary and non-boundary cases. These are special cases of more general asymptotic results that we provide concerning the estimation of the ratio of conditional expectations of two functions of the response variable. We also provide a good bandwidth selection method for the estimators. Examples of application, limited simulation results and discussion of related problems and approaches are also given.     

Career Compromise Types Among University Graduates During the School‐to‐Work Transition

Because of high youth unemployment caused by structural conditions, South Korean university graduates must compromise their employment preferences and instead accept whatever work is available. In this study, we classified the types of compromises using latent profile analysis to examine various factors involved in the career compromise of 472 recent university graduates during their school‐to‐work transition. We identified four types of compromise patterns with distinct characteristics and discovered that the university graduates who did not compromise their interest and aptitude in their job selection showed a higher level of commitment to their career compared with those who compromised. Results suggest that individuals who do not compromise their interests and aptitudes are more likely to have successful and fulfilling long‐term careers.     

Marital Relationships Following the Korean Economic Crisis: Applying the Family Stress Model

In response to the recent economic crisis in Korea and its negative effects on families, the current study examined the interrelationships among economic pressure, emotional distress, marital conflict, and marital satisfaction for 236 Korean couples. The family stress model ( Conger & Elder, 1994 ; Conger, Rueter, & Conger, 2000 ; Conger, Rueter, & Elder, 1999 ) was tested using structural equation modeling. The results generally supported the theoretical model, showing that economic pressure negatively affects marital satisfaction via emotional distress and marital conflict. The results also implied cultural differences in the process of family stress. Korean husbands' emotional distress did not affect marital conflict or marital satisfaction, suggesting that Korean husbands may differ from their wives in their reaction to emotional distress from economic pressure.     

Critical appraisal of Bayesian dynamic borrowing from an imperfectly commensurate historical control

Bayesian dynamic borrowing designs facilitate borrowing information from historical studies. Historical data, when perfectly commensurate with current data, have been shown to reduce the trial duration and the sample size, while inflation in the type I error and reduction in the power have been reported, when imperfectly commensurate. These results, however, were obtained without considering that Bayesian designs are calibrated to meet regulatory requirements in practice and even no‐borrowing designs may use information from historical data in the calibration. The implicit borrowing of historical data suggests that imperfectly commensurate historical data may similarly impact no‐borrowing designs negatively. We will provide a fair appraiser of Bayesian dynamic borrowing and no‐borrowing designs. We used a published selective adaptive randomization design and real clinical trial setting and conducted simulation studies under varying degrees of imperfectly commensurate historical control scenarios. The type I error was inflated under the null scenario of no intervention effect, while larger inflation was noted with borrowing. The larger inflation in type I error under the null setting can be offset by the greater probability to stop early correctly under the alternative. Response rates were estimated more precisely and the average sample size was smaller with borrowing. The expected increase in bias with borrowing was noted, but was negligible. Using Bayesian dynamic borrowing designs may improve trial efficiency by stopping trials early correctly and reducing trial length at the small cost of inflated type I error.     

Parent Prevention Communication Profiles and Adolescent Substance Use: A Latent Profile Analysis and Growth Curve Model

ABSTRACT

This current study identifies distinct parent prevention communication profiles and examines whether youth with different parental communication profiles have varying substance use trajectories over time. Eleven schools in two rural school districts in the Midwestern United States were selected, and 784 students were surveyed at three time points from the beginning of 7th grade to the end of 8th grade. A series of latent profile analyses were performed to identify discrete profiles/subgroups of substance-specific prevention communication (SSPC). The results revealed a 4-profile model of SSPC: Active-Open, Passive-Open, Active-Silent, and Passive-Silent. A growth curve model revealed different rates of lifetime substance use depending on the youth’s SSPC profile. These findings have implications for parenting interventions and tailoring messages for parents to fit specific SSPC profiles.     

Meta‐analysis of depression among marriage‐based migrant women in South Korea

Using meta‐analysis, this study examines the effect sizes of the variables related to depression and the moderating effects of depression among marriage‐based migrant women in South Korea to determine the implications for human service fields. This study identified 25 peer‐reviewed articles from 2000 to 2014 published in either Korean or in English. Results showed that (i) Korean language proficiency and economic hardship had significant effect sizes relative to depression; (ii) the psychosocial characteristics (i.e., acculturative stress, social support, marital satisfaction, life satisfaction, and self‐esteem) of this population had medium effect sizes relative to depression; and (iii) use of the Center for Epidemiological Studies Depression scale, residence in agricultural areas, average age, and average length of stay in Korea had significant moderating effects. Based on these results, the authors discuss social work practices and policies for this population, suggesting the priorization of marriage‐based migrant women in agricultural areas who have lived in Korea for short lengths of time.     

A mixed control chart for monitoring failure times under accelerated hybrid censoring

In an accelerated hybrid censoring scheme several stress factors can be accelerated to make the products to respond to fail more quickly than under normal operating conditions. In such situations, the control charts available in the literature cover the attribute characteristics only to monitor the performance of the process over time. This study extends the idea by proposing an optimal mixed attribute-variable control chart for Weibull distribution under an accelerated hybrid censoring scheme keeping the advantages of both attribute and variable control charts. It first monitors the number of defectives under accelerated conditions and switches to the variable control chart to investigate the mean failure times when the process stability is dubious. The performance of the proposed chart is evaluated by using run-length characteristics, and the optimality of the design parameter is achieved by minimizing the out-of-control average run length. The simulation study depicted better performance of the proposed control chart than the traditional charts in detecting shifts in the process. A real-life application is also included.KEYWORDS: Mixed control chart, attribute chart, variable chart, Weibull distribution, accelerated hybrid censoring     

Negatively interdependent preferences

We develop a theory of representation of interdependent preferences that reflect the widely acknowledged phenomenon of keeping up with the Joneses (i.e. of those preferences which maintain that well-being depend on “relative standing” in the society as well as on material consumption). The principal ingredient of our analysis is the assumption that individuals desire to occupy a (subjectively) better position than their peers. This is quite a primitive starting point in that it does not give any reference to what is actually regarded as “status” in the society. We call this basic postulate negative interdependence, and study its implications. In particular, combining this assumption with some other basic postulates that are widely used in a number of other branches of the theory of individual choice, we axiomatize the relative income hypothesis, and obtain an operational representation of interdependent preferences. Received: 7 December 1998/Accepted: 24 August 1999