A joint modelling approach for clustered recurrent events and death events

In dental implant research studies, events such as implant complications including pain or infection may be observed recurrently before failure events, i.e. the death of implants. It is natural to assume that recurrent events and failure events are correlated to each other, since they happen on the same implant (subject) and complication times have strong effects on the implant survival time. On the other hand, each patient may have more than one implant. Therefore these recurrent events or failure events are clustered since implant complication times or failure times within the same patient (cluster) are likely to be correlated. The overall implant survival times and recurrent complication times are both interesting to us. In this paper, a joint modelling approach is proposed for modelling complication events and dental implant survival times simultaneously. The proposed method uses a frailty process to model the correlation within cluster and the correlation within subjects. We use Bayesian methods to obtain estimates of the parameters. Performance of the joint models are shown via simulation studies and data analysis.     

Deviations From Desired Age at Marriage: Mental Health Differences Across Marital Status

Although several factors condition mental health differences between married and never‐married adults, given recent increases in marriage delay and permanent singlehood, one modifying factor—deviation from desired age at marriage—has yet to be examined. Using data from the National Longitudinal Survey of Youth 1979 (N = 7,277), the author tested whether deviation from desired age at marriage shapes the mental health of married and never‐married adults as well as mental health differences between them. The results showed that most respondents failed to meet their initial preference for age at marriage. Marrying both earlier and later than desired (compared to on time) resulted in poorer mental health and fewer benefits compared to never marrying. For the never‐married, mental health was best, and differences compared to the married were nonsignificant, for those nearest their desired age at marriage. As timing deviations increased, however, a mental health deficit among the never‐married emerged.     

突发公共事件应对中的行政权威及其尺度

我国继SARS、禽流感之后又遭受了较为严重的狂犬病疫情袭击。在这些事件的应对中,政府权力行使所暴露的缺陷依然如故,引起人们的广泛关注。笔者分析了突发公共事件应对中行政权力行使的必要性,认为在应对突发公共事件中,必须树立民主与权威相结合的指导原则;同时,必须根据权力法定、权益保护、公共评价、比例原则和制度体系这五个因素来综合制定评判标准以明确行政权力行使的界限。     

Additive Transformation Models for Recurrent Events

In this article, we propose a class of additive transformation models for recurrent event data, which includes the additive rates model as a special case. The new models offer great flexibility in formulating the effects of covariates on the mean function of recurrent events. Estimating equation approaches are developed for the model parameters, and asymptotic properties of the resulting estimators are established. In addition, a model checking procedure is presented to assess the adequacy of the model. The finite sample performance of the proposed estimators is examined through simulation studies, and an application to a bladder cancer study is presented.     

Social media processes in disasters: Implications of emergent technology use

This article seeks to extend social science scholarship on social media technology use during disruptive events. Though social media's role in times of crisis has been previously studied, much of this work tends to focus on first-responders and relief organizations. However, social media use during disasters tends to be decentralized and this organizational structure can promote different types of messages to top-down information systems. Using 142,786 geo-tagged tweets collected before and after Hurricane Sandy's US landfall as a case study, this article seeks to explore shifts in social media behavior during disruptive events and highlights that though Sandy disrupted routine life within Twitter, users responded to the disaster by employing humor, sharing photos, and checking into locations. We conclude that social media use during disruptive events is complex and understanding these nuanced behaviors is important across the social sciences.     

Risk of Extreme Events in Multiobjective Decision Trees Part 1. Severe Events

Earlier work with decision trees identified nonseparability as an obstacle to minimizing the conditional expected value, a measure of the risk of extreme events, by the well-known method of averaging out and folding back. This first of two companion papers addresses the conditional expected value that is defined as the expected outcome assuming the exceedance of a threshold β, where β is preselected by the decision maker. An approach is proposed to overcome the need to evaluate all policies in order to identify the optimal policy. The approach is based on the insight that the conditional expected value is separable into two constituent elements of risk and can thus be optimized along with other objectives, including the unconditional expected value of the outcome, by using a multiobjective decision tree. An example of sequential decision making for improving highway capacity is given.     

Exploring the Moderating Influence of Delinquent Peers on the Link Between Trauma, Anger, and Violence Among Male Youth: Implications for Social Work Practice

This study’s objective was to explore the influence of delinquent peer exposure, on the relationship between male youths’ histories of trauma, anger, and violent behavior. Using a nationally representative sample of male adolescents aged 12–17 and self report interviews, information was gathered on their levels of exposure to violence, stressful life events (SLE), anger, depression, delinquent peer exposure, and violent behavior. Results of a moderation analyses revealed that youth who reported higher levels of exposure to trauma, anger, and delinquent peers were at an increased risk for anger and for violent offending. Delinquent peer exposure exerted a significant interaction effect on the relationship between anger and violent offending. The implications for prevention and intervention efforts are delineated.     

农民工培训的逆向选择及破解对策分析

加快农村富余劳动力转移就业的关键就在于加强农民工培训。目前,政府对农民工培训的投入力度正在逐年加大;但用人单位对农民工培训却缺乏积极性,其深层次原因在于农民工培训市场的“逆向选择”问题。破解对策就是农民工通过“信号传递”的方式使企业了解到其个人素质的完全信息,这样企业将针对高素质农民工与低素质农民工制定不同的服务合同。政府在农民工培训过程中要加强政策导向投入、财政支付投入以及技能凭证管理投入。     

非对称信息下证券公司道德风险定价模型的研究

由于证券市场上非对称信息状态的存在,信息差别给证券投资者保护制度带来了不容忽视的道德风险结果,本文通过建立证券公司道德风险定价模型,计算出了证券公司向证券投资者保护基金机构缴纳保护基金的费率基准。据此,在保护证券投资者利益的基础上,证券投资者保护基金机构可以向证券公司按照给出的费率基准收取保护基金,从而减少证券公司道德风险的发生。     

Multiobjective Decision-Tree Analysis1

Single-objective-based decision-tree analysis has been extensively and successfully used in numerous decision-making problems since its formal introduction by Howard Raiffa more than two decades ago. This paper extends the traditional methodology to incorporate multiple noncommensurate objective functions and use of the conditional expected value of the risk of extreme and catastrophic events. The proposed methodology considers the cases where (a) a finite number of actions are available at each decision node and (b) discrete or continuous states of nature can be presented at each chance node. The proposed extension of decision-tree analysis is introduced through an example problem that leads the reader step-by-step into the methodological procedure. The example problem builds on flood warning systems. Two noncommensurate objectives—the loss of lives and the loss of property (including monetary costs of the flood warning system)–are incorporated into the decision tree. In addition, two risk measures—the common expected value and the conditional expected value of extreme and catastrophic events—are quantified and are also incorporated into the decision-making process. Theoretical difficulties associated with the stage-wise calculation of conditional expected values are identified and certain simplifying assumptions are made for computational tractibility. In particular, it is revealed that decisions concerning experimentation have a very interesting impact on the noninferior solution set of options—a phenomenon that has no equivalence in the single-objective case.