Items bundles

An item bundle is a small group of multiple choice items that share a common reading passage or graph, or a small group of matching items that share distractors. Item bundles are easily identified by paging through a copy of a test. Bundled items may violate the latent conditional independence assumption of unidimensional item response theory (IRT), but such a violation would not typically suggest the existence of a new fundamental human ability to read one specific reading passage or to interpret one specific graph. It is important, therefore, to have theoretical concepts and empirical checks that distinguish between, on the one hand, anticipated violations of latent conditional independence within item bundles, and, on the other hand, violations that cannot be attributed to idiosyncratic features of test format and instead suggest departures from unidimensionalty. To this end, two theorems on unidimensional IRT are extended to describe observable item response distributions when there is conditional independencebetween but not necessarilywithin item bundles.The author is grateful to Ivo Molenaar and the referees for many helpful suggestions, and to D. Thayer for assistance with computing.     

Maximum likelihood estimation of polyserial correlations

This paper considers a multivariate normal model with one of the component variables observable only in polytomous form. The maximum likelihood approach is used for estimation of the parameters in the model. The Newton-Raphson algorithm is implemented to obtain the solution of the problem. Examples based on real and simulated data are reported.The research of the first author was supported in part by a research grant (DA01070) from the US Public Health Service. We are indebted to the referees and the editor for some very valuable comments and suggestions.     

初二学生知觉到的教师期望、自我价值感与自我效能的关系研究

以 2 55名初中二年级学生为被试 ,采用验证性因素分析和多元回归方法对教师期望、自我价值感及自我效能的关系进行研究。结果表明 :(1 )人口统计学变量 (性别和班别 )对教师期望、自我价值感及自我效能有影响。 (2 )教师期望与自我价值感和自我效能相关显著 :积极效应与自我价值感及自我效能的各维度呈显著正相关 ,消极效应与自我价值感及自我效能各维度呈显著负相关。 (3 )在控制了人口统计学变量后 ,教师期望与自我价值感仍对自我效能各维度具有较强的预测作用。 (4)自我价值感在教师期望对自我效能各维度的影响上起到了中介作用     

在亚健康状态研究中运用结构方程模型的合理性

亚健康状态是处于健康与疾病之间的一种“非病但非健康”的中间状态,主要表现为躯体、心理和社会适应等方面的不适,目前尚没有公认的概念和测量诊断工具。由于亚健康状态研究数据中含有潜变量、测量误差以及变量间关系需要确定等因素,不能使用传统的统计学方法进行处理。结构方程模型能够同时处理观测变量、潜变量、测量误差及变量间的关系,应用结构方程模型验证亚健康状况测量量表的结构效度和亚健康状态理论模型是非常合理的。     

Factor analysis with (mixed) observed and latent variables in the exponential family

We develop a general approach to factor analysis that involves observed and latent variables that are assumed to be distributed in the exponential family. This gives rise to a number of factor models not considered previously and enables the study of latent variables in an integrated methodological framework, rather than as a collection of seemingly unrelated special cases. The framework accommodates a great variety of different measurement scales and accommodates cases where different latent variables have different distributions. The models are estimated with the method of simulated likelihood, which allows for higher dimensional factor solutions to be estimated than heretofore. The models are illustrated on synthetic data. We investigate their performance when the distribution of the latent variables is mis-specified and when part of the observations are missing. We study the properties of the simulation estimators relative to maximum likelihood estimation with numerical integration. We provide an empirical application to the analysis of attitudes.     

Effects of magnitude of food reinforcement on free-operant response rates

In Experiment 1 rats were trained to press a lever on a variable-ratio schedule of food presentation and were then exposed to progressively increasing magnitudes of food reinforcement. Response running rates (rates exclusive of the postreinforcement pause) were found to increase as a function of increasing reinforcement magnitudes. The effect of reinforcement magnitude on response rates inclusive of the postreinforcement pause, however, was less pronounced. Increases in the magnitude of reinforcement were also found to increase the length of the postreinforcement pause. Rats in Experiment 2 were trained to respond on a chained differential-reinforcement-of-low-rate variable-ratio schedule, and were exposed to increasing magnitudes of reinforcement as in Experiment 1. Response running rates increased in the variable-ratio component but decreased in the other component of the schedule. The results are discussed with reference to incentive accounts of reinforcement and the action of reinforcement on the response units generated by the operative contingencies.