Essential independence and likelihood-based ability estimation for polytomous items

A definition ofessential independence is proposed for sequences of polytomous items. For items satisfying the reasonable assumption that the expected amount of credit awarded increases with examinee ability, we develop a theory ofessential unidimensionality which closely parallels that of Stout. Essentially unidimensional item sequences can be shown to have a unique (up to change-of-scale) dominant underlying trait, which can be consistently estimated by a monotone transformation of the sum of the item scores. In more general polytomous-response latent trait models (with or without ordered responses), anM-estimator based upon maximum likelihood may be shown to be consistent for under essentially unidimensional violations of local independence and a variety of monotonicity/identifiability conditions. A rigorous proof of this fact is given, and the standard error of the estimator is explored. These results suggest that ability estimation methods that rely on the summation form of the log likelihood under local independence should generally be robust under essential independence, but standard errors may vary greatly from what is usually expected, depending on the degree of departure from local independence. An index of departure from local independence is also proposed.This work was supported in part by Office of Naval Research Grant N00014-87-K-0277 and National Science Foundation Grant NSF-DMS-88-02556. The author is grateful to William F. Stout for many helpful comments, and to an anonymous reviewer for raising the questions addressed in section 2. A preliminary version of section 6 appeared in the author's Ph.D. thesis.     

The use of latent class models for assessing prerequisite relations and transference among traits

This paper presents a strategy for pairwise assessment which may be used to evaluate the nature of both prerequisite and transference relations existing among a set of traits. This strategy is appropriate for use both within a confirmatory context, in which an attempt is made to establish the validity of some specified set of relations among traits, as well as within an exploratory context, in which a search is made for unconjectured prerequisite and transference relations existing between pairs of traits. Both uses of this strategy are based on a variety of latent class models which are representative of various possible relational states existing between pairs of traits. Thus, the nature of trait relations may be investigated through the use of statistical assessments of both absolute and relative fit attained by these models. An application is presented to exemplify how this strategy may be used within the exploratory context.The author is obliged to Clifford Clogg, C. Mitchell, Dayton, and William Schafer for helpful comments made regarding a previous draft of this paper as well as to Mary Papageorgiou who provided access to the data which was considered in this study.     

The polyserial correlation coefficient

The polyserial and point polyserial correlations are discussed as generalizations of the biserial and point biserial correlations. The relationship between the polyserial and point polyserial correlation is derived. The maximum likelihood estimator of the polyserial correlation is compared with a two-step estimator and with a computationally convenient ad hoc estimator. All three estimators perform reasonably well in a Monte Carlo simulation. Some practical applications of the polyserial correlation are described.By coincidence, the first author and the second and third authors learned that they were working independently on closely related problems and, consequently, decided to write a jointly authored paper.     

Correlation and prediction in ordinal test theory

Based on the test theory model for ordinal measurements proposed by Schulman and Haden, the present paper considers correlations between tests, attenuation, regressions involving true and observed scores, and prediction of test reliability.The population correlation between tests is shown to be related to the expected sample correlation for samples of sizen ₁ andn ₂. Errors of estimation, measurement and prediction are found to be similar to their counterparts in interval test theory, while attenuation is identical to its counterpart. The bias in estimating population reliability from sample data is compared for Kendall's tau and Spearman's rho.The author wishes to thank the referees for their helpful comments on an earlier draft of this paper, and in particular, for the suggested alternative methods of establishing some of the presented results.     

特质焦虑与青少年冒险行为的关系：基于双系统模型的机制探讨

为了考察特质焦虑与青少年冒险行为的关系并基于双系统模型探究其中的影响机制,本研究采用特质焦虑问卷、简版自我控制量表、感觉寻求量表和青少年多领域冒险行为问卷对1720名12～18岁的青少年进行问卷调查,共回收有效数据1549份。结果发现：（1）特质焦虑能正向预测青少年的冒险行为,自我控制在特质焦虑与冒险行为间的关系中起中介作用;（2）感觉寻求调节了该中介过程的后半路径,即个体的感觉寻求水平越高,自我控制对冒险行为的预测作用越大。     

高低特质攻击个体对威胁面部表情识别的差异研究——来自ERP的证据

为揭示高特质攻击个体对愤怒、恐惧威胁面部表情识别的特点及其电生理机制，本研究采用Buss-Perry攻击问卷选取高低特质攻击个体26名和27名为被试，采用面孔识别范式对高低特质攻击个体识别威胁面部表情时的ERP差异进行研究。结果发现，在愤怒、恐惧表情上，高特质攻击组在N170成分的潜伏期都显著短于低特质攻击组；在愤怒、恐惧表情上，高特质攻击组在P200成分的波幅都显著高于低特质攻击组。这表明高特质攻击个体对愤怒、恐惧威胁面部表情的识别具有高度敏感性，这种敏感性体现在面部表情识别的早期和中期阶段，而非晚期阶段，即高特质攻击个体在早期的前注意阶段就对愤怒、恐惧威胁面部表情进行优先注意；在中期的注意阶段，高特质攻击个体可以很好地确认愤怒、恐惧威胁面部表情。     

The impacts of ignoring individual mobility across clusters in estimating a piecewise growth model

A three-level piecewise growth model (3L-PGM) can be used to break up nonlinear growth into multiple components, providing the opportunity to examine potential sources of variation in individual and contextual growth within different segments of the model. The conventional 3L-PGM assumes that the data are strictly hierarchical in nature, where measurement occasions (level 1) are nested within individuals (level 2) who are members of a single cluster (level 3). However, in longitudinal research, it is sometimes difficult for data structures to remain purely clustered during a study, such as when some students change classrooms or schools over time. One resulting data structure in this situation is known as a multiple membership structure, where some lower-level units are members of more than one higher-level unit. The new multiple membership PGM (MM-PGM) extends the 3L-PGM to handle multiple membership data structures frequently found in the social sciences. This study sought to examine the consequences of ignoring individual mobility across clusters when estimating a 3L-PGM in comparison to estimating a MM-PGM. MM-PGM estimates were less biased (especially in the cluster-level coefficient estimates), although we found substantial bias in cluster-level variance components across some conditions for both models.     

特质感恩与状态感恩对初中生合作水平的影响

为探究感恩对初中生合作水平的影响,本研究采用追踪调查与实验相结合的方法,通过两个研究分别探究了特质感恩与内在的合作倾向,状态感恩与外在的合作行为之间的关系。结果发现：（1）初中女生的特质感恩、人物取向感恩显著高于男生;初一下的合作倾向显著低于初一上、初二上时期;（2）初中生的特质感恩水平能显著正向预测合作倾向,状态感恩的唤起会增加公共物品困境中的合作行为。