The many null distributions of person fit indices

This paper deals with the situation of an investigator who has collected the scores ofn persons to a set ofk dichotomous items, and wants to investigate whether the answers of all respondents are compatible with the one parameter logistic test model of Rasch. Contrary to the standard analysis of the Rasch model, where all persons are kept in the analysis and badly fittingitems may be removed, this paper studies the alternative model in which a small minority ofpersons has an answer strategy not described by the Rasch model. Such persons are called anomalous or aberrant. From the response vectors consisting ofk symbols each equal to 0 or 1, it is desired to classify each respondent as either anomalous or as conforming to the model. As this model is probabilistic, such a classification will possibly involve false positives and false negatives. Both for the Rasch model and for other item response models, the literature contains several proposals for a person fit index, which expresses for each individual the plausibility that his/her behavior follows the model. The present paper argues that such indices can only provide a satisfactory solution to the classification problem if their statistical distribution is known under the null hypothesis that all persons answer according to the model. This distribution, however, turns out to be rather different for different values of the person's latent trait value. This value will be called ability parameter, although our results are equally valid for Rasch scales measuring other attributes.As the true ability parameter is unknown, one can only use its estimate in order to obtain an estimated person fit value and an estimated null hypothesis distribution. The paper describes three specifications for the latter: assuming that the true ability equals its estimate, integrating across the ability distribution assumed for the population, and conditioning on the total score, which is in the Rasch model the sufficient statistic for the ability parameter.Classification rules for aberrance will be worked out for each of the three specifications. Depending on test length, item parameters and desired accuracy, they are based on the exact distribution, its Monte Carlo estimate and a new and promising approximation based on the moments of the person fit statistic. Results for the likelihood person fit statistic are given in detail, the methods could also be applied to other fit statistics. A comparison of the three specifications results in the recommendation to condition on the total score, as this avoids some problems of interpretation that affect the other two specifications.The authors express their gratitude to the reviewers and to many colleagues for comments on an earlier version.     

A critical review of theS/L reliability index

The meaning and properties of a commonly used index of reliability, S/L,were examined critically. It was found that the index does not reflect any conventional concept of reliability. When used for an identical behavioral observation session, it is not statistically correlated with other reliability indices. Within an observation session, the standardizing measure of Lis beyond the control of the investigator. Furthermore, the reason for the choice of Las the standard is unclear. The role of chance agreement in S/Lis not known. The exact interpretation of the index depends on which observer reports L.Overall the conceptual and mathematical meaning of S/Lis dubious. It is suggested that the S/Lindex should not be used until its nature is shown to be a measure of reliability. Other approaches such as the intraclass correlations and generalizability coefficients should be used instead.The authors are indebted to Johnny Matson for his critique of an earlier version of this paper.     

AN INDEX FOR ASSESSING WEIGHT CHANGE IN CHILDREN: WEIGHT/HEIGHT RATIOS1

Weight and height data from two studies were recomputed, and original data were computed using a Weight Index formula that accounts for the interaction of actual weight/height changes in growing children and compares this ratio with that of normed weight/height ratios for equal-aged children. Recomputing the data of one study showed that the Weight Index is a more sensitive procedure for assessing long-term behavioral treatment of obesity for girls than weight alone. Recomputing the data of a second study showed that the Weight Index formula is consistent for boys and girls and is a more sensitive procedure for assessing long-term effects of a variety of medical treatments for obesity than the Ponderal Index or weight alone. Computation of the data for 17 “normal” children in a preschool class showed a zero Weight Index score before and after a six-month interval elapsed without treatment. The procedure may be useful in assessing ponderosity or anorexia over intervals of six months or more with growing children or difference between actual and normed weight over shorter intervals.     

On the optimality of the simultaneous redundancy transformations

The objective of this paper is to introduce and motivate additional properties and interpretations for the redundancy variables. It is shown that these variables can be derived by application of certain invariance arguments and without reference to the index of redundancy. In addition, an optimality property for the variables is presented which is important whenever one restricts attention in a study to a subset of the redundancy variables. This optimality property pertains to the subset rather than to the individual variables.This paper is based in part on the author's doctoral dissertation, Department of Statistics, Princeton, University. Research was conducted under the supervision of Lawrence S. Mayer.     

正确认识与评价SCI

发表《科学引文索引》 (science citation index, SCI) 论文的多少和论文被引用率的高低, 是国际上通用的评价基础研究成果水平的标准。引进SCI的概念, 对促进我国的科研评价标准化和国际化发挥了积极作用。SCI目前已经成为我国评价科研成果的重要指标, 某些地方甚至成为唯一指标。但SCI主要侧重在基础学科领域的评价, 不能涵盖全面的科技评价。在肯定SCI对规范我国科研的评价体系的积极作用的同时, 对其负面影响也不能忽视。以上海中医药大学为例, 通过介绍SCI和国内SCI论文发表的现状, 对正确认识和全面评价SCI的作用提出建议。     

Equal prioritisation does not yield lower levels of participation in physical activities than higher prioritisation

ObjectivesThis study examined whether individuals who assigned equal priority to physical activity and an alternative activity exhibited lower levels of participation in physical activities than individuals who assigned higher priority to physical activity than an alternative activity. In addition, we examined whether a measure of prioritisation derived from an algebraic difference index provided a rigorous test of prioritisation effects.DesignWe employed a two-wave prospective design that aimed to predict physical activity participation.MethodPrioritisation, intentions and perceptions of control were measured at the first wave of data collection. After five weeks, we administered follow-up measures of behavioural conflict and physical activity participation.ResultsA hierarchical regression analysis showed that although the algebraic difference index was positively associated with measures of physical activity participation, equal prioritisation did not yield lower levels of physical activity participation than high prioritisation.ConclusionsFindings suggest that equal prioritisation is not a less optimal self-regulatory strategy than high prioritisation in the domain of physical activity. Regression coefficients associated with algebraic difference indexes should be interpreted with caution and consider analyses that examine effects of component measures of prioritisation on physical activity participation.     

SCI,不能没,不能唯——以广州医科大学为例

研究了广州医科大学2004年~2014年的SCI论文总量、总被引频次、篇均被引量、论文被引率、高被引论文、热门论文等数据。结果发现,广州医科大学近10年SCI论文总数大幅上升,但篇均被引频次偏低;"沉睡"论文较多,高被引论文和热门论文较少,尖端成果少。提出"不能没SCI",但要正确使用SCI,学术评价应该由重"收录"向重"引用"转变;应引入分学科、分层评估的机制,鼓励发表高水平论文。同时提出"不能唯SCI",以该校人才评估的两个案例为依据,分析了将h指数和F1000两项指标纳入学术评价体系的可行性。     

结构方程模型检验：拟合指数与卡方准则

讨论了Hu和Bentler（1998,1999）推荐的检验结构方程模型的7个拟合指数准则,对这7个指数的历史、特点和表现做了比较详细的述评。指出了他们基于这7个指数的单指数准则和2-指数准则的不足之处。提出了超低显著性水平下的卡方准则,并部分重复他们的模拟例子,将卡方准则与这7个指数准则比较,结果说明新的卡方准则优于其中的6个,与另一个相当。最后简要说明了应当如何检视拟合指数进行模型检验和模型比较。     

The Relationships Among Sensory Processing Styles,Personality Traits,and Body Mass Index: A Pilot Study

The purpose of the authors in this study is to explore the possible relationships among sensory processing styles, possible sensory processing disorders, personality traits, and body mass index. There is research on the relationship between obesity as defined by body mass index and temperament, and sensory processing and temperament; however, no information could be found on the relationship between body mass index and sensory processing styles, or the role that temperament and personality styles may play in these relationships. The 50 female participants were recruited from the University of New England community. The sample included women between the ages of 19 and 59 years, and of various weights. None of the participants had a history of thyroid problems, diabetes, or any physical disabilities that would limit daily physical activity. None had been diagnosed with sensory processing disorder. All participants filled out two self-reports and a demographic questionnaire. The Adult/Adolescent Sensory Profile (Brown &; Dunn, 2002 Brown , C. E. , &; Dunn , W. ( 2002 ). Adult/Adolescent Sensory Profile . San Antonio , TX : The Psychological Corporation . [Google Scholar]) determines a person's sensory processing style and possible sensory processing disorder, and the Basic Personality Inventory (Jackson, 1996 Jackson , D. N. ( 1996 ). Basic Personality Inventory Manual , (2nd ed.) . Port Huron , MI : Sigma Assessment  [Google Scholar]) focuses on everyday behaviors to describe temperament and “adult behavioral syndromes” (p. 5). Through this study the authors show only tentative relationships between body mass index and sensory processing styles and personality traits. The data could be interpreted to support both discriminant and convergent validity between the Adult/Adolescent Sensory Profile and the Basic Personality Inventory. There were, however, significant correlations between aspects of sensory processing and aspects of personality that appeared to strengthen the idea that differences in sensory processing result in predictable types of behavior, indicating that sensory processing disorders are a separate diagnostic category.     

Female physical attractiveness in Britain and Malaysia: a cross-cultural study

Two purported cues to perceived female physical attractiveness are body mass index (BMI) and body shape as measured by the waist-to-hip ratio (WHR). This study examined the relative contribution of both cues in several culturally socio-economically distinct populations. Six hundred and eighty-two participants from Britain and Malaysia were asked to rate a set of images of real women with known BMI and WHR. The results showed that BMI is the primary determinant of female physical attractiveness, whereas WHR failed to emerge as a significant predictor. The results also showed that there were significant differences in preferences for physical attractiveness along a gradient of socio-economic development, with urban participants preferring images of women with significantly lower BMIs than their rural counterparts. The findings are discussed in terms of evolutionary psychological explanations of mate selection, and sociocultural theory, which emphasises the learning of preferences for body sizes in social and cultural contexts.