Bayesian dynamic models for survival data with a cure fraction

In this paper, we propose a new class of semi-parametric cure rate models. Specifically, we construct dynamic models for piecewise hazard functions over a finite partition of the time axis. Allowing the size of partition and the levels of baseline hazard to be random, our proposed models provide a great flexibility in controlling the degree of parametricity in the right tail of the survival distribution and the amount of correlations among the log-baseline hazard levels. Several properties of the proposed models are derived, and propriety of the implied posteriors with improper noninformative priors for regression coefficients based on the proposed models is established for the fixed partition of the time axis. In addition, an efficient reversible jump computational algorithm is developed for carrying out posterior computation. A real data set from a melanoma clinical trial is analyzed in detail to further demonstrate the proposed methodology.     

逊志自得与法古创新--朝鲜王朝后期实学性的两条思惟之路

朝鲜王朝后期实学研究的两大流派可以说是星湖学派与北学派.从思维的论法来考察这两大流派的共同与不同点,并通过这些考察从宏观的角度重新探讨实学的性格.星湖学派的李瀷主唱逊志自得说法来做为经学的指针或者思维的论法,而北学派的朴趾源提出法古与创新做为作文的指针或者思维的论法.逊志自得的论法在形式上设定了他者与主体间的紧张,而实际上含蓄着对主体的自觉与对它的志向.北学派的法古创新论法虽然在形式上设定着上古与现在间的紧张,但实际上还含蓄着对现在的觉醒与信赖.     

What drives successful social networking services? A comparative analysis of user acceptance of Facebook and Twitter

This study identifies perceived mobility, security, connectedness, system and service quality, usefulness, attitude, and flow experience as key motivational factors for using social networking services (SNSs), and develops a theoretical model that explicates the process in which users adopt Facebook and Twitter by integrating these factors with the technology acceptance model (TAM). While results of structural equation modeling (SEM) on the collected data (N = 2,214) verified the validity and reliability of the research model, Facebook and Twitter users were found to emphasize different motivational factors when deciding to use SNSs. The implications of notable findings and directions for future studies are discussed.     

Optimal Configuration of a Square Array Group Testing Algorithm

We consider the optimal configuration of a square array group testing algorithm (denoted A2) to minimize the expected number of tests per specimen. For prevalence greater than 0.2498, individual testing is shown to be more efficient than A2. For prevalence less than 0.2498, closed form lower and upper bounds on the optimal group sizes for A2 are given. Arrays of dimension 2 × 2, 3 × 3, and 4 × 4 are shown to never be optimal. The results are illustrated by considering the design of a specimen pooling algorithm for detection of recent HIV infections in Malawi.     

Understanding the origin of the Bohai state in the Democratic People’s Republic of Korea

The state of Bohai (on Korean reading – Parhae, ??) existed in what is modern Russian Primorye region (Приморский край/Maritime Region), North Korea and Northeastern China, from the late seventh to the early tenth centuries AD. It played an important role in the history of the area as a major regional power for over two centuries. Recently, the history of Bohai has begun to attract scholarly interest. However, North Korean studies of Bohai remain basically almost unknown in the Western world. In this article, I present the history of Bohai studies in the Democratic People’s Republic of Korea (DPRK). In this article, I analyze not only North Korean studies of Bohai but also the opinions of the Korean scholars on the subject. They are rather specific for North Koreans who have unique access to the archaeological and historical materials on Bohai but are also subjected to unusually severe political pressures. The history of Bohai has now become an object of active political games which are related to territorial claims based on alleged archaeological and historical material. This situation increases the general interest in Bohai but also makes honest and unbiased research more difficult.     

Infants born preterm and infants born full-term generate more selective leg joint movement during the scaffolded mobile task

Infants born very preterm (PT), prior to 32 weeks gestation, are at increased risk of developing cerebral palsy. Children with spastic cerebral palsy have impaired selective leg joint movement, which contributes to lifelong walking limitations. We investigated whether infants born PT generated more selective hip–knee joint movement (e.g., hip flexes as knee extends) while participating in a scaffolded mobile task. Infants born PT and infants born full-term (FT) at 4 months corrected age participated in a scaffolded mobile task for 2–3 consecutive days. The scaffolded mobile task required infants to raise their legs vertically over a virtual threshold. Three threshold heights (low, middle, and high) were used to test whether the middle and high heights encourage infants to move their legs more selectively. Fifteen infants born FT learned the task and showed more selective hip–knee movement at each of the three threshold heights on the day that they learned, compared with their baseline spontaneous kicking. Thirteen infants born PT learned the task and showed more selective hip–knee movement on their learning day, but only when the middle and high thresholds were used. The results show that the scaffolded mobile task effectively encouraged infants to generate more selective hip–knee joint movement.     

Variance estimation of DEE and regression estimator when a first-phase cluster sample is restratified

We consider a variance estimation when a stratified single stage cluster sample is selected in the first phase and a stratified simple random element sample is selected in the second phase. We propose explicit formulas of (asymptotically), we propose explicit formulas of (asymptotically) unbiased variance estimators for the double expansion estimator and regression estimator. We perform a small simulation study to investigate the performance of the proposed variance estimators. In our simulation study, the proposed variance estimator showed better or comparable performance to the Jackknife variance estimator. We also extend the results to a two-phase sampling design in which a stratified pps with replacement cluster sample is selected in the first phase.     

Sleepless in school? The social dimensions of young people’s bedtime rest and routines

There are increasing concerns that social pressures, such as family changes and social media, are ‘invading’ the sanctuary of the bedroom with the result that students arrive at school tired and stressed. This paper seeks to examine whether these concerns are justified and contribute to the growing literature on the social dimensions of sleep through examining the rest and routines of two cohorts of young people aged 12–13 and 14–15 years old. Our research indicates that, in general, most young people have ‘reasonable’ amounts of sleep and routines. But, a significant proportion does go to school tired, with apparent negative consequences for their well-being. The paper examines some of the within-cohort variations, in particular, the significance of volume of sleep, routines and engagement with social media and how these may reflect the material and cultural circumstances of the young people. The paper concludes by arguing for more research on the complex social causes and consequences of sleep deprivation among today’s youth.     

Practical statistical considerations for investigating anti-tumor treatments in mice

Anti-tumor treatment outcomes in mouse experiments can be challenging to interpret and communicate accurately. In reporting these experiments, rigorous statistical considerations are commonly absent, although statistical applications have been proposed. We investigated the practicality and utility of different statistical strategies for the analysis of anti-tumor responses in a longitudinal mouse case study. Each analysis that we performed had different endpoints, investigated different questions, and was based on different assumptions. We found rudimentary visual and risk analysis insufficient without additional considerations, and upon further investigation we found improvements in key anti-tumor parameter estimates associated with a drug combination in our case study. We offer practical statistical considerations for investigating anti-cancer treatments in mice, applying a multi-tier statistical approach.     

Time to care: socioeconomic,family, and workplace factors in men and women’s parental leave use

ABSTRACT

Parental leave has important benefits for women, men, and families. This study examines how individual, family, and workplace factors are associated with the length of parental leaves taken by workers in diverse jobs and work contexts, but with the same employer, focusing on gender differences in the factors associated with longer parental leaves. The data are the result of a collaboration between university researchers and a municipal employer. We find that gender was a major driver of the duration of parental leaves for these workers, who must use their accumulated paid time off or take unpaid leave for parental leave; women’s leaves were almost three times longer than men’s. We also find gender differences in the factors associated with leave duration. For women, socioeconomic status seemed to matter most, while for men, family and workplace context influenced leave length. The results indicate the centrality of financial considerations in parents’ leave decisions, reinforcing the importance of having a dedicated paid parental leave policy. We argue that paid parental leaves would help reduce disparities between and within genders at work and in the family.