Obtaining the best value for money in adaptive sequential estimation

In [Kujala, J. V., Richardson, U., &; Lyytinen, H. (2010). A Bayesian-optimal principle for learner-friendly adaptation in learning games. Journal of Mathematical Psychology, 54(2), 247–255], we considered an extension of the conventional Bayesian adaptive estimation framework to situations where each observable variable is associated with a certain random cost of observation. We proposed an algorithm that chooses each placement by maximizing the expected gain in utility divided by the expected cost. In this paper, we formally justify this placement rule as an asymptotically optimal solution to the problem of maximizing the expected utility of an experiment that terminates when the total cost overruns a given budget. For example, the cost could be defined as the random time taken by each trial in an experiment, and one might wish to maximize the expected total information gain over as many trials as can be completed in 15 min. A simple, analytically tractable example is considered.     

Coherence shifts in probabilistic inference tasks

The fast‐and‐frugal heuristics approach to probabilistic inference assumes that individuals often employ simple heuristics to integrate cue information that commonly function in a non‐reciprocal fashion. Specifically, the subjective validity of a certain cue remains stable during the application of a heuristic and is not changed by the presence or absence of another cue. The parallel constraint satisfaction (PCS) model, in contrast, predicts that information is processed in a reciprocal fashion. Specifically, it assumes that subjective cue validities interactively affect each other and are modified to coherently support the favored choice. Corresponding to the model's simulation, we predicted the direction and the size of such coherence shifts. Cue validities were measured before, after (Experiment 1), and during judgment (Experiments 2 and 3). Coherence shifts were found in environments involving real‐world cue knowledge (weather forecasts) and in a domain for which the application of fast‐and‐frugal heuristics has been demonstrated (city‐size tasks). The results indicate that subjective cue validities are not fixed parameters, but that they are interactively changed to form coherent representations of the task. Copyright © 2009 John Wiley & Sons, Ltd.     

Adaptive Memory: Identifying the Proximate Roots of the Survival Processing Advantage

The current study examined the role of item-specific, relational, and elaborative processing on adaptive memory. Younger and older adults received the standard survival processing, a survival-short, or a pleasantness processing instruction. The survival-short condition was specifically included to lead to fewer possibilities to engage in elaborative processing. Furthermore, half of the presented words were categorized words to boost relational processing. Younger adults demonstrated the typical survival recall advantage in that standard survival processing instructions resulted in superior free recall performance than that of the survival-short and the pleasantness processing groups. Among older adults, no mnemonic benefit of standard survival processing relative to the survival-short or pleasantness processing groups was found. Furthermore, reducing the probability of elaborative processing (i.e., through the survival-short processing instructions) abolished the survival recall advantage. Our results thus provide further evidence for the role of item-specific, relational, and elaborative processing in the survival processing advantage.     

Selecting the Right Tool For the Job

There are competing ethical concerns when it comes to designing any clinical research study. Clinical trials of possible treatments for Ebola virus are no exception. If anything, the competing ethical concerns are exacerbated in trying to find answers to a deadly, rapidly spreading, infectious disease. The primary goal of current research is to identify experimental therapies that can cure Ebola or cure it with reasonable probability in infected individuals. Pursuit of that goal must be methodologically sound, practical and consistent with prevailing norms governing human subjects research. Some maintain that only randomized controlled trials (RCTs) with a placebo or standard-of-care arm can meet these conditions. We maintain that there are alternative trial designs that can do so as well and that sometimes these are preferable to RCTs.     

Occupational stress,psychological burnout and anxiety

Abstract

For many decades, the stress process was described primarily in terms of negative emotions. However, robust evidence that positive emotions co-occurred with negative emotions during intensely stressful situations suggested the need to consider the possible roles of positive emotions in the stress process. About 10 years ago, these possibilities were incorporated into a revision of stress and coping theory (Folkman, 1997). This article summarizes the research reported during the intervening 10 years that pertains to the revised model. Evidence has accumulated regarding the co-occurrence of positive and negative emotions during stressful periods; the restorative function of positive emotions with respect to physiological, psychological, and social coping resources; and the kinds of coping processes that generate positive emotions including benefit finding and reminding, adaptive goal processes, reordering priorities, and infusing ordinary events with positive meaning. Overall, the evidence supports the propositions set forth in the revised model. Contrary to earlier tendencies to dismiss positive emotions, the evidence indicates they have important functions in the stress process and are related to coping processes that are distinct from those that regulate distress. Including positive emotions in future studies will help address an imbalance between research and clinical practice due to decades of nearly exclusive concern with the negative emotions.     

药物临床试验设计的伦理思考

目前广泛采用的药物临床试验设计中,由于不能使受试者最大限度的受益而在伦理学方面存在弊端。自适应设计方法的出现,为克服这一弊端提供了现实途径,可使药物临床试验的受试者能够最大程度的受益。本文从传统临床试验引发的伦理问题入手,阐述了自适应设计以人为本的特点,探讨了其在解决伦理与疗效冲突问题中的重要作用。     

计算机化自适应测验选题策略述评

计算机化自适应测验(computerized adaptive testing, CAT)是基于测量理论和计算机技术的一种测验模式。它根据考生的作答反应自适应地选择测验项目。选题策略是CAT的重要组成部分之一, 关系到测量效率、测验安全和测验信、效度等重要问题。根据CAT是否具有非统计约束对传统CAT和认知诊断CAT的选题策略进行了分类介绍, 未来研究应进一步提高选题策略的综合表现、深入探讨多级评分项目和认知诊断CAT的选题策略。     

结合a分层的兼具项目曝光和广义测验重叠率控制的选题策略

测验安全和题库使用率在计算机化自适应测验中十分重要, 特别是高风险测验。传统的SHGT法兼具同时控制项目曝光率和广义测验重叠率的功能, 但题库使用率较差。a分层法能够提高题库使用率, 但对过度曝光的项目控制不足。本研究将a分层法的思想与SHGT法相结合, 各取所长, 提出了3种新的选题方法：SHGT_a法, SHGT_b法和SHGT_c法。研究结果表明：(1)与SHGT法相比, 新方法均可以在有效地控制项目曝光率和广义测验重叠率同时, 极大地提高题库使用率; (2)随着预设项目曝光率(rmax)和广义测验重叠率( )取值的增大以及共享人数a的减小, 新方法对被试能力估计的精度呈上升趋势。比起SHGT法, 新方法仍能保持很高的题库使用率; (3)当区分度和难度的相关(rab)较大时, SHGT_b和SHGT_c法在能力估计精度方面优于SHGT_a法; (4)在不同的测验考察内容比例下, 3种新方法对被试能力估计的精度均较好; (5)与SHGT法相比, 新方法能够有效地控制项目曝光率过度控制的问题。     

计算机化自适应测验在认知诊断中的应用

作为认知诊断与计算机化自适应测验相结合的产物, 认知诊断计算机化自适应测验(Cognitive Diagnostic Computerized Adaptive Testing, CD-CAT)是对被试知识状态的自适应。它既有传统CAT所面临的普遍性问题, 也有在认知诊断中遇到的特殊问题：由于认知诊断中涉及属性这一概念, CD-CAT与传统CAT有很大的差别。本文紧紧围绕属性引起的差异, 分别从认知诊断模型、题库建设、起始规则、选题策略、被试知识状态估计和终止规则等几部分详细介绍CD-CAT的研究进展和存在的问题。