Improved Transferability of Data‐Driven Damage Models Through Sample Selection Bias Correction

Damage models for natural hazards are used for decision making on reducing and transferring risk. The damage estimates from these models depend on many variables and their complex sometimes nonlinear relationships with the damage. In recent years, data‐driven modeling techniques have been used to capture those relationships. The available data to build such models are often limited. Therefore, in practice it is usually necessary to transfer models to a different context. In this article, we show that this implies the samples used to build the model are often not fully representative for the situation where they need to be applied on, which leads to a “sample selection bias.” In this article, we enhance data‐driven damage models by applying methods, not previously applied to damage modeling, to correct for this bias before the machine learning (ML) models are trained. We demonstrate this with case studies on flooding in Europe, and typhoon wind damage in the Philippines. Two sample selection bias correction methods from the ML literature are applied and one of these methods is also adjusted to our problem. These three methods are combined with stochastic generation of synthetic damage data. We demonstrate that for both case studies, the sample selection bias correction techniques reduce model errors, especially for the mean bias error this reduction can be larger than 30%. The novel combination with stochastic data generation seems to enhance these techniques. This shows that sample selection bias correction methods are beneficial for damage model transfer.     

Statistical testing strategies for assessing treatment efficacy and marker accuracy in phase III trials

When a candidate predictive marker is available, but evidence on its predictive ability is not sufficiently reliable, all‐comers trials with marker stratification are frequently conducted. We propose a framework for planning and evaluating prospective testing strategies in confirmatory, phase III marker‐stratified clinical trials based on a natural assumption on heterogeneity of treatment effects across marker‐defined subpopulations, where weak rather than strong control is permitted for multiple population tests. For phase III marker‐stratified trials, it is expected that treatment efficacy is established in a particular patient population, possibly in a marker‐defined subpopulation, and that the marker accuracy is assessed when the marker is used to restrict the indication or labelling of the treatment to a marker‐based subpopulation, ie, assessment of the clinical validity of the marker. In this paper, we develop statistical testing strategies based on criteria that are explicitly designated to the marker assessment, including those examining treatment effects in marker‐negative patients. As existing and developed statistical testing strategies can assert treatment efficacy for either the overall patient population or the marker‐positive subpopulation, we also develop criteria for evaluating the operating characteristics of the statistical testing strategies based on the probabilities of asserting treatment efficacy across marker subpopulations. Numerical evaluations to compare the statistical testing strategies based on the developed criteria are provided.     

Blinded continuous monitoring in clinical trials with recurrent event endpoints

In studies with recurrent event endpoints, misspecified assumptions of event rates or dispersion can lead to underpowered trials or overexposure of patients. Specification of overdispersion is often a particular problem as it is usually not reported in clinical trial publications. Changing event rates over the years have been described for some diseases, adding to the uncertainty in planning. To mitigate the risks of inadequate sample sizes, internal pilot study designs have been proposed with a preference for blinded sample size reestimation procedures, as they generally do not affect the type I error rate and maintain trial integrity. Blinded sample size reestimation procedures are available for trials with recurrent events as endpoints. However, the variance in the reestimated sample size can be considerable in particular with early sample size reviews. Motivated by a randomized controlled trial in paediatric multiple sclerosis, a rare neurological condition in children, we apply the concept of blinded continuous monitoring of information, which is known to reduce the variance in the resulting sample size. Assuming negative binomial distributions for the counts of recurrent relapses, we derive information criteria and propose blinded continuous monitoring procedures. The operating characteristics of these are assessed in Monte Carlo trial simulations demonstrating favourable properties with regard to type I error rate, power, and stopping time, ie, sample size.     

On the estimation of non linear functions in stochastic volatility models

Abstract

This paper focuses on the inference of suitable generally non linear functions in stochastic volatility models. In this context, in order to estimate the variance of the proposed estimators, a moving block bootstrap (MBB) approach is suggested and discussed. Under mild assumptions, we show that the MBB procedure is weakly consistent. Moreover, a methodology to choose the optimal length block in the MBB is proposed. Some examples and simulations on the model are also made to show the performance of the proposed procedure.     

Modifications of sequential designs in bioequivalence trials

Bioequivalence (BE) studies are designed to show that two formulations of one drug are equivalent and they play an important role in drug development. When in a design stage, it is possible that there is a high degree of uncertainty on variability of the formulations and the actual performance of the test versus reference formulation. Therefore, an interim look may be desirable to stop the study if there is no chance of claiming BE at the end (futility), or claim BE if evidence is sufficient (efficacy), or adjust the sample size. Sequential design approaches specially for BE studies have been proposed previously in publications. We applied modification to the existing methods focusing on simplified multiplicity adjustment and futility stopping. We name our method modified sequential design for BE studies (MSDBE). Simulation results demonstrate comparable performance between MSDBE and the original published methods while MSDBE offers more transparency and better applicability. The R package MSDBE is available at https://sites.google.com/site/modsdbe/ . Copyright © 2015 John Wiley & Sons, Ltd.     

Contextual identity experiencing facilitates resilience in Native American academics

This article discusses the socio-cultural dynamics that interact with ethno-racial identity experiencing in a previously under-researched group. A qualitative interdisciplinary study with 40 Native American academics from 28 mainstream universities across the U.S. served as a case example with findings that contrasted with historically influential theoretical frameworks postulating identity confusion and conflicts at the intersection of one’s mainstream education and profession versus one’s ethno-racial community grounding. Instead of feeling pressure to identify with only one worldview, the contextual, dynamic identities associated with the inclusive and flexible self-concept of tribal participants allowed them to in turn take advantage of two divergent cultural meaning systems pertaining to their distinct socio-cultural contexts. These shifts were experienced as not endogenous but rather exogenous variables, which did not cause the historically theorized issues. Participants felt their tribal identities instead facilitated meaningful integration of the existing incongruences, which resulted in unexpectedly resilient subjective experiencing.     

Becoming Custodial Dads: Exploring Parenting Among Low‐Income and Working‐Class African American Fathers

The authors use an ecological framework and grounded theoretical analysis to explore the circumstances in which working‐class and low‐income custodial African American fathers gain custody of their children, their transition from part‐time to full‐time parents, and the role of support networks in enhancing or inhibiting these men's parenting. Twenty‐four men from an impoverished Midwestern urban area participated in the study. The findings suggest that these men, and perhaps others sharing their demographic profiles, generally become parents by default and are often reluctant to take on a full‐time, single parenting role. Adaptation to the role seems to be enhanced by these men's use of extended kin support networks and shared living arrangements. However, low wages, a lack of sufficient assistance from public assistance programs, and informal custody arrangements often inhibit their fathering.     

"20世纪文艺复兴"的重要篇章--两次大战期间的美国小说思潮述评

两次世界大战期间的美国小说,成就尤显卓著.它作为综合体现美利坚民族文化意识的最重要文学样式,充分显示了美国文学的现代性、多样性和独创性,并从不同的侧面,反映了发达的资本主义社会背景下的各种冲突和矛盾,刻印着社会心理嬗变的轨迹.     

试论美国电影中的英雄情结

“英雄类”影片是好莱坞制造的最具轰动效应的神话之一。本文拟对美国影片中塑造的各类英雄形象加以梳理与阐释 ,并进而对这些英雄片背后的英雄情结进行剖析 ,以期管窥美国影片中一些深层文化心理机制     

一曲美国南方没落贵族的挽歌--评威廉·福克纳的《喧嚣与骚动》

《喧嚣与骚动》是美国现代著名作家威廉·福克纳的惊世之作。在小说中 ,福克纳刻画了一幅美国旧南方贵族没落的图景 ,为没落的旧南方贵族弹奏了一曲凄凉的挽歌 ,深刻地揭示了美国旧南方的衰败。本文从不同的角度来体现小说深刻的思想主题及作品鲜明的艺术特色