A Hierarchical Rater Model for Constructed Responses,with a Signal Detection Rater Model

The hierarchical rater model (HRM) re‐cognizes the hierarchical structure of data that arises when raters score constructed response items. In this approach, raters’ scores are not viewed as being direct indicators of examinee proficiency but rather as indicators of essay quality; the (latent categorical) quality of an examinee's essay in turn serves as an indicator of the examinee's proficiency, thus yielding a hierarchical structure. Here it is shown that a latent class model motivated by signal detection theory (SDT) is a natural candidate for the first level of the HRM, the rater model. The latent class SDT model provides measures of rater precision and various rater effects, above and beyond simply severity or leniency. The HRM‐SDT model is applied to data from a large‐scale assessment and is shown to provide a useful summary of various aspects of the raters’ performance.     

The Consistency of Student Proficiency Classifications Under Competing IRT Models

States are implementing statewide assessment programs that classify students into proficiency levels that reflect state-defined performance standards. In an effort to provide support for score interpretations, this study examined the consistency of classifications based on competing item response theory (IRT) models for data from a state assessment program. Classification of students into proficiency levels was compared based on a 1-parameter vs. a 3-parameter IRT model. Despite an overall high level of agreement between classifications based on the 2 models, systematic differences were observed. Under the 1-parameter model, proficiency was underestimated for low proficiency classifications but overestimated for upper proficiency classifications. This resulted in higher "Below Basic" and "Advanced" classifications under 1-parameter vs. 3-parameter IRT applications. Implications of these differences are discussed.     

基于CTT、GT、IRT的评分者信度研究——以某届奥运会女子跳水决赛为例

本文以某届国际奥林匹克运动会女子跳水决赛为例,综合应用CTT、GT和IRT三大测量理论进行评分者信度分析,从不同角度揭示评分者之间和评分者内部的差异情况。结果表明:CTT的评分者信度分别为0.981和078;GT的概化系数和可靠性指数分别为0.8279和0.8271,比赛中所采用的7名评委分别对选手在5轮上的跳水表现进行评定的决策是比较适宜的决策;在IRT中,相对而言,评委5在7名评委中最为严厉,评委2最为宽松,但评委之间在宽严程度上的差异不显著,评委1和评委4在自身一致性上存在问题,不同评委在评定不同选手、不同难度系数动作和不同轮数上存在偏差,但未达到显著性水平。基于本文的分析,可以了解三种评分者信度分析方法的特点及各自优势,为评分者培训和提高评分信度提供有用信息。     

An NCME Instructional Module on Item‐Fit Statistics for Item Response Theory Models

Drawing valid inferences from item response theory (IRT) models is contingent upon a good fit of the data to the model. Violations of model‐data fit have numerous consequences, limiting the usefulness and applicability of the model. This instructional module provides an overview of methods used for evaluating the fit of IRT models. Upon completing this module, the reader will have an understanding of traditional and Bayesian approaches for evaluating model‐data fit of IRT models, the relative advantages of each approach, and the software available to implement each method.     

A Nonparametric Approach to Estimate Classification Accuracy and Consistency

When cut scores for classifications occur on the total score scale, popular methods for estimating classification accuracy (CA) and classification consistency (CC) require assumptions about a parametric form of the test scores or about a parametric response model, such as item response theory (IRT). This article develops an approach to estimate CA and CC nonparametrically by replacing the role of the parametric IRT model in Lee's classification indices with a modified version of Ramsay's kernel‐smoothed item response functions. The performance of the nonparametric CA and CC indices are tested in simulation studies in various conditions with different generating IRT models, test lengths, and ability distributions. The nonparametric approach to CA often outperforms Lee's method and Livingston and Lewis's method, showing robustness to nonnormality in the simulated ability. The nonparametric CC index performs similarly to Lee's method and outperforms Livingston and Lewis's method when the ability distributions are nonnormal.     

A Nonparametric Approach for Assessing Goodness-of-Fit of IRT Models in a Mixed Format Test

Investigating the fit of a parametric model plays a vital role in validating an item response theory (IRT) model. An area that has received little attention is the assessment of multiple IRT models used in a mixed-format test. The present study extends the nonparametric approach, proposed by Douglas and Cohen (2001), to assess model fit of three IRT models (three- and two-parameter logistic model, and generalized partial credit model) used in a mixed-format test. The statistical properties of the proposed fit statistic were examined and compared to S-X² and PARSCALE’s G². Overall, RISE (Root Integrated Square Error) outperformed the other two fit statistics under the studied conditions in that the Type I error rate was not inflated and the power was acceptable. A further advantage of the nonparametric approach is that it provides a convenient graphical inspection of the misfit.     

ESTIMATING THE RELIABILITY, VALIDITY, AND INVALIDITY OF ESSAY RATINGS

In an essay rating study multiple ratings may be obtained by having different raters judge essays or by having the same rater(s) repeat the judging of essays. An important question in the analysis of essay ratings is whether multiple ratings, however obtained, may be assumed to represent the same true scores. When different raters judge the same essays only once, it is impossible to answer this question. In this study 16 raters judged 105 essays on two occasions; hence, it was possible to test assumptions about true scores within the framework of linear structural equation models. It emerged that the ratings of a given rater on the two occasions represented the same true scores. However, the ratings of different raters did not represent the same true scores. The estimated intercorrelations of the true scores of different raters ranged from .415 to .910. Parameters of the best fitting model were used to compute coefficients of reliability, validity, and invalidity. The implications of these coefficients are discussed.     

Generalizability in Item Response Modeling

An approach called generalizability in item response modeling (GIRM) is introduced in this article. The GIRM approach essentially incorporates the sampling model of generalizability theory (GT) into the scaling model of item response theory (IRT) by making distributional assumptions about the relevant measurement facets. By specifying a random effects measurement model, and taking advantage of the flexibility of Markov Chain Monte Carlo (MCMC) estimation methods, it becomes possible to estimate GT variance components simultaneously with traditional IRT parameters. It is shown how GT and IRT can be linked together, in the context of a single-facet measurement design with binary items. Using both simulated and empirical data with the software WinBUGS, the GIRM approach is shown to produce results comparable to those from a standard GT analysis, while also producing results from a random effects IRT model.     

On the Use of IRT Models With Judgmental Standard Setting Procedures

In judgmental standard setting procedures (e.g., the Angoff procedure), expert raters establish minimum pass levels (MPLs) for test items, and these MPLs are then combined to generate a passing score for the test. As suggested by Van der Linden (1982), item response theory (IRT) models may be useful in analyzing the results of judgmental standard setting studies. This paper examines three issues relevant to the use of lRT models in analyzing the results of such studies. First, a statistic for examining the fit of MPLs, based on judges' ratings, to an IRT model is suggested. Second, three methods for setting the passing score on a test based on item MPLs are analyzed; these analyses, based on theoretical models rather than empirical comparisons among the three methods, suggest that the traditional approach (i.e., setting the passing score on the test equal to the sum of the item MPLs) does not provide the best results. Third, a simple procedure, based on generalizability theory, for examining the sources of error in estimates of the passing score is discussed.     

Extended Mixed‐Effects Item Response Models With the MH‐RM Algorithm

A mixed‐effects item response theory (IRT) model is presented as a logical extension of the generalized linear mixed‐effects modeling approach to formulating explanatory IRT models. Fixed and random coefficients in the extended model are estimated using a Metropolis‐Hastings Robbins‐Monro (MH‐RM) stochastic imputation algorithm to accommodate for increased dimensionality due to modeling multiple design‐ and trait‐based random effects. As a consequence of using this algorithm, more flexible explanatory IRT models, such as the multidimensional four‐parameter logistic model, are easily organized and efficiently estimated for unidimensional and multidimensional tests. Rasch versions of the linear latent trait and latent regression model, along with their extensions, are presented and discussed, Monte Carlo simulations are conducted to determine the efficiency of parameter recovery of the MH‐RM algorithm, and an empirical example using the extended mixed‐effects IRT model is presented.     

An Instructional Module on Mokken Scale Analysis

Mokken scale analysis (MSA) is a probabilistic‐nonparametric approach to item response theory (IRT) that can be used to evaluate fundamental measurement properties with less strict assumptions than parametric IRT models. This instructional module provides an introduction to MSA as a probabilistic‐nonparametric framework in which to explore measurement quality, with an emphasis on its application in the context of educational assessment. The module describes both dichotomous and polytomous formulations of the MSA model. Examples of the application of MSA to educational assessment are provided using data from a multiple‐choice physical science assessment and a rater‐mediated writing assessment.     

A Technical Note on IRT Simulation Studies: Dealing With Truth,Estimates, Observed Data,and Residuals

Simulation studies are extremely common in the item response theory (IRT) research literature. This article presents a didactic discussion of “truth” and “error” in IRT‐based simulation studies. We ultimately recommend that future research focus less on the simple recovery of parameters from a convenient generating IRT model, and more on practical comparative estimation studies when the data are intentionally generated to incorporate nuisance dimensionality and other sources of nuanced contamination encountered with real data. A new framework is also presented for conceptualizing and comparing various residuals in IRT studies. The new framework allows even very different calibration and scoring IRT models to be compared on a common, convenient, and highly interpretable number‐correct metric. Some illustrative examples are included.     

Comparing the Fit of Item Response Theory and Factor Analysis Models

Linear factor analysis (FA) models can be reliably tested using test statistics based on residual covariances. We show that the same statistics can be used to reliably test the fit of item response theory (IRT) models for ordinal data (under some conditions). Hence, the fit of an FA model and of an IRT model to the same data set can now be compared. When applied to a binary data set, our experience suggests that IRT and FA models yield similar fits. However, when the data are polytomous ordinal, IRT models yield a better fit because they involve a higher number of parameters. But when fit is assessed using the root mean square error of approximation (RMSEA), similar fits are obtained again. We explain why. These test statistics have little power to distinguish between FA and IRT models; they are unable to detect that linear FA is misspecified when applied to ordinal data generated under an IRT model.     

IRT Approaches to Modeling Scores on Mixed-Format Tests

This article considers psychometric properties of composite raw scores and transformed scale scores on mixed-format tests that consist of a mixture of multiple-choice and free-response items. Test scores on several mixed-format tests are evaluated with respect to conditional and overall standard errors of measurement, score reliability, and classification consistency and accuracy under three item response theory (IRT) frameworks: unidimensional IRT (UIRT), simple structure multidimensional IRT (SS-MIRT), and bifactor multidimensional IRT (BF-MIRT) models. Illustrative examples are presented using data from three mixed-format exams with various levels of format effects. In general, the two MIRT models produced similar results, while the UIRT model resulted in consistently lower estimates of reliability and classification consistency/accuracy indices compared to the MIRT models.     

Comparing the Difficulty of Examination Subjects with Item Response Theory

Methods are presented for comparing grades obtained in a situation where students can choose between different subjects. It must be expected that the comparison between the grades is complicated by the interaction between the students' pattern and level of proficiency on one hand, and the choice of the subjects on the other hand. Three methods based on item response theory (IRT) for the estimation of proficiency measures that are comparable over students and subjects are discussed: a method based on a model with a unidimensional representation of proficiency, a method based on a model with a multidimensional representation of proficiency, and a method based on a multidimensional representation of proficiency where the stochastic nature of the choice of examination subjects is explicitly modeled. The methods are compared using the data from the Central Examinations in Secondary Education in the Netherlands. The results show that the unidimensional IRT model produces unrealistic results, which do not appear when using the two multidimensional IRT models. Further, it is shown that both the multidimensional models produce acceptable model fit. However, the model that explicitly takes the choice process into account produces the best model fit.     

How Often Is the Misfit of Item Response Theory Models Practically Significant?

Standard 3.9 of the Standards for Educational and Psychological Testing ( 1999 ) demands evidence of model fit when item response theory (IRT) models are employed to data from tests. Hambleton and Han ( 2005 ) and Sinharay ( 2005 ) recommended the assessment of practical significance of misfit of IRT models, but few examples of such assessment can be found in the literature concerning IRT model fit. In this article, practical significance of misfit of IRT models was assessed using data from several tests that employ IRT models to report scores. The IRT model did not fit any data set considered in this article. However, the extent of practical significance of misfit varied over the data sets.     

Conditional Standard Errors of Measurement for Scale Scores Using IRT

An IRT method for estimating conditional standard errors of measurement of scale scores is presented, where scale scores are nonlinear transformations of number-correct scores. The standard errors account for measurement error that is introduced due to rounding scale scores to integers. Procedures for estimating the average conditional standard error of measurement for scale scores and reliability of scale scores are also described. An illustration of the use of the methodology is presented, and the results from the IRT method are compared to the results from a previously developed method that is based on strong true-score theory.     

Evaluating Rater Accuracy in Performance Assessments

A new method for evaluating rater accuracy within the context of performance assessments is described. Accuracy is defined as the match between ratings obtained from operational raters and those obtained from an expert panel on a set of benchmark, exemplar, or anchor performances. An extended Rasch measurement model called the FACETS model is presented for examining rater accuracy. The FACETS model is illustrated with 373 benchmark papers rated by 20 operational raters and an expert panel. The data are from the 1993field test of the High School Graduation Writing Test in Georgia. The data suggest that there are statistically significant differences in rater accuracy; the data also suggest that it is easier to be accurate on some benchmark papers than on others. A small example is presented to illustrate how the accuracy ordering of raters may not be invariant over different subsets of benchmarks used to evaluate accuracy.     

Item Response Theory Models for Performance Decline During Testing

Sometimes, test‐takers may not be able to attempt all items to the best of their ability (with full effort) due to personal factors (e.g., low motivation) or testing conditions (e.g., time limit), resulting in poor performances on certain items, especially those located toward the end of a test. Standard item response theory (IRT) models fail to consider such testing behaviors. In this study, a new class of mixture IRT models was developed to account for such testing behavior in dichotomous and polytomous items, by assuming test‐takers were composed of multiple latent classes and by adding a decrement parameter to each latent class to describe performance decline. Parameter recovery, effect of model misspecification, and robustness of the linearity assumption in performance decline were evaluated using simulations. It was found that the parameters in the new models were recovered fairly well by using the freeware WinBUGS; the failure to account for such behavior by fitting standard IRT models resulted in overestimation of difficulty parameters on items located toward the end of the test and overestimation of test reliability; and the linearity assumption in performance decline was rather robust. An empirical example is provided to illustrate the applications and the implications of the new class of models.     

An Extension of Four IRT Linking Methods for Mixed-Format Tests

Under item response theory (IRT), linking proficiency scales from separate calibrations of multiple forms of a test to achieve a common scale is required in many applications. Four IRT linking methods including the mean/mean, mean/sigma, Haebara, and Stocking-Lord methods have been presented for use with single-format tests. This study extends the four linking methods to a mixture of unidimensional IRT models for mixed-format tests. Each linking method extended is intended to handle mixed-format tests using any mixture of the following five IRT models: the three-parameter logistic, graded response, generalized partial credit, nominal response (NR), and multiple-choice (MC) models. A simulation study is conducted to investigate the performance of the four linking methods extended to mixed-format tests. Overall, the Haebara and Stocking-Lord methods yield more accurate linking results than the mean/mean and mean/sigma methods. When the NR model or the MC model is used to analyze data from mixed-format tests, limitations of the mean/mean, mean/sigma, and Stocking-Lord methods are described.