拓广分部评分模型下计算机自适应测验变加权选题策略

摘要: 在计算机自适应测验中, 对0-1评分模型按a-分层选题是高效安全的策略,但多级评分模型的项目难度/步骤参数有多个而无法直接应用这种选题策略。信息函数能够很好地综合项目所有参数及能力参数,但最大信息量选题策略会影响考试安全。本文提出一种变加权选题策略,它通过调用一个与信息量相关联的函数,该函数与信息量成正比,与区分度的某个幂函数成反比,从而达到既能综合项目所有参数又按a分层的效果。在GPCM模型下用蒙特卡罗实验进行比较研究,结果显示新的选题策略总体效果比已有相关结果好。     

Accounting for fluctuations in body dissatisfaction

The present study evaluated whether the strength of relationship between contextual cues (presence of company and mood) and state body dissatisfaction varied as a function of individual differences in key trait measures (body shame, body surveillance tendencies, internalization of appearance standards, and trait affect) which have been linked to trait body dissatisfaction. Fifty-five undergraduate women completed a questionnaire containing the trait-based measures and then carried a Personal Digital Assistant (PDA) for a 7-day period. The PDA prompted participants six times daily to self-report their current mood and state body dissatisfaction. Multi-level modeling revealed that individual differences in body shame predicted inter-individual variability in the strength of the relationships between presence of company and state body dissatisfaction, and positive mood and state body dissatisfaction. Trait positive affect also explained variance in the positive mood state-body dissatisfaction relationship. The implications of the findings for prevention of body image disturbances are discussed.     

Hiding in plain sight: Older U.S. purpose exemplars

ABSTRACT

Despite significant research on purpose in adolescence and early adulthood, little is known about purpose in older adults. This paper defines purpose as ongoing commitment to and sustained action toward goals that are meaningful to the self and aim to contribute beyond the self. This study of purpose in later life draws on interviews of 102 respondents drawn from a U.S. nationally representative sample of 1198 men and women aged 50–92. Eighteen interviewees are identified as exemplars of purpose beyond the self and are matched with a comparison group of non-purposeful peers. Interview coding revealed that, in contrast to the non-purposeful comparison group, the purpose exemplars describe their lives as including several interconnected sources of well-being: purpose beyond the self, positive relationships, positive life engagement, a sense of competence, and freedom balanced with the desire to contribute. Implications for practitioners and the public are discussed.     

The selective directed forgetting effect: Can people forget only part of a text?

Participants studied sentences describing two different characters and then were told to forget the sentences about only one of the characters. A second list contained sentences attributed to a third character. Subsequently, they received a recall test on the sentences about the original two characters. When the sentences could be thematically integrated, participants showed no directed forgetting relative to a control group that was never told to forget. However, with unrelated sentences, participants selectively forgot the target character's sentences without forgetting the other character's sentences. This selective directed forgetting effect is a novel empirical result. We interpret the results as consistent with Radvansky's (1999) ideas about inhibition with textual materials.     

The lateral effects of Dohsa-method relaxation on visual and auditory responses

The effects of relaxation training, using the Dohsa method, on visual and auditory responses were examined. Twelve college students underwent relaxation training either to the left shoulder, left side of the waist, and the left foot, or to the right side. The measures used in this study were weight-bearing, body perception and external perception, visual field, and visual and hearing acuity. Weight-bearing significantly increased for the foot undergoing relaxation training, compared with the untreated foot, indicating that the subjects stood more firmly on the ground on the relaxed foot. Subjects could also perceive positive changes in their "sense of standing firmly on the ground,""sense of activity in the body,""sense of muscular relaxation," and "sense of fullness in the abdomen" on the side of the body receiving relaxation training. There were positive changes in external perception such as "vividness of the external world,""breadth of the visual field," and "active impression of the external world" for subjects' vision on the side receiving relaxation training. Furthermore, visual and hearing acuity on the side on which relaxation training was administered improved significantly.     

Empirical bayes estimates of domain scores under binomial and hypergeometric distributions for test scores

We introduce two simple empirical approximate Bayes estimators (EABEs)— and —for estimating domain scores under binomial and hypergeometric distributions, respectively. Both EABEs (derived from corresponding marginal distributions of observed test scorex without relying on knowledge of prior domain score distributions) have been proven to hold -asymptotic optimality in Robbins' sense of convergence in mean. We found that, where and are the monotonized versions of and under Van Houwelingen's monotonization method, respectively, the convergence rate of the overall expected loss of Bayes risk in either or depends on test length, sample size, and ratio of test length to size of domain items. In terms of conditional Bayes risk, and outperform their maximum likelihood counterparts over the middle range of domain scales. In terms of mean-squared error, we also found that: (a) given a unimodal prior distribution of domain scores, performs better than both and a linear EBE of the beta-binomial model when domain item size is small or when test items reflect a high degree of heterogeneity; (b) performs as well as when prior distribution is bimodal and test items are homogeneous; and (c) the linear EBE is extremely robust when a large pool of homogeneous items plus a unimodal prior distribution exists.The authors are indebted to both anonymous reviewers, especially Reviewer 2, and the Editor for their invaluable comments and suggestions. Thanks are also due to Yuan-Chin Chang and Chin-Fu Hsiao for their help with our simulation and programming work.     

A conservative inverse normal test procedure for combining p-values in integrative research

The use ofp-values in combining the results of independent studies often involves studies that are potentially aberrant either in quality or in actual values. A robust data analysis suggests the use of a statistic that takes these aberrations into account by trimming some of the largest and smallestp-values. We present a trimmed statistic based on an inverse cumulative normal transformation of the orderedp-values, together with a simple and convenient method for approximating the distribution and first two moments of this statistic.The author thanks Ingram Olkin, David Rogosa, Jim Hodges and two anonymous reviewers for providing many useful comments and suggestions.     

弱智儿童在上课时和自由活动时的行为表现

研究了４１名弱智儿童。采用时间样本的方法收集材料,以期从动态角度了解弱智儿童在上课时和自由活动时的行为表现。按园别和智力落后程度两个方面对被试在上课时的８大类行为和自由活动时的７大类行为进行了分析。结果发现：班级人数、不同教学方法和智力落后程度与弱智儿童的行为表现有关。还对收集材料的方法、园别和智力落后程度与弱智儿童的行为表现的关系、高频率的自娱活动等,进行了讨论。最后,根据研究结果对教师提出了教学建议。     

Casuistry in medical ethics: Rehabilitated,or repeat offender?

For a number of reasons, casuistry has come into vogue in medical ethics. Despite the frequency with which it is avowed, the application of casuistry to issues in medical ethics has been given virtually no systematic defense in the ethics literature. That may be for good reason, since a close examination reveals that casuistry delivers much less than its advocates suppose, and that it shares some of the same weaknesses as the principle-based methods it would hope to supplant.     

A latent class unfolding model for analyzing single stimulus preference ratings

A multidimensional unfolding model is developed that assumes that the subjects can be clustered into a small number of homogeneous groups or classes. The subjects that belong to the same group are represented by a single ideal point. Since it is not known in advance to which group of class a subject belongs, a mixture distribution model is formulated that can be considered as a latent class model for continuous single stimulus preference ratings. A GEM algorithm is described for estimating the parameters in the model. The M-step of the algorithm is based on a majorization procedure for updating the estimates of the spatial model parameters. A strategy for selecting the appropriate number of classes and the appropriate number of dimensions is proposed and fully illustrated on some artificial data. The latent class unfolding model is applied to political science data concerning party preferences from members of the Dutch Parliament. Finally, some possible extensions of the model are discussed.The first author is supported as Bevoegdverklaard Navorser of the Belgian Nationaal Fonds voor Wetenschappelijk Onderzoek. Part of this paper was presented at the Distancia meeting held in Rennes, France, June 1992.