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1.
Many statistics used in the assessment of differential item functioning (DIF) in polytomous items yield a single item-level index of measurement invariance that collapses information across all response options of the polytomous item. Utilizing a single item-level index of DIF can, however, be misleading if the magnitude or direction of the DIF changes across the steps underlying the polytomous response process. A more comprehensive approach to examining measurement invariance in polytomous item formats is to examine invariance at the level of each step of the polytomous item, a framework described in this article as differential step functioning (DSF). This article proposes a nonparametric DSF estimator that is based on the Mantel-Haenszel common odds ratio estimator ( Mantel & Haenszel, 1959 ), which is frequently implemented in the detection of DIF in dichotomous items. A simulation study demonstrated that when the level of DSF varied in magnitude or sign across the steps underlying the polytomous response options, the DSF-based approach typically provided a more powerful and accurate test of measurement invariance than did corresponding item-level DIF estimators.  相似文献   

2.
Researchers interested in exploring substantive group differences are increasingly attending to bundles of items (or testlets): the aim is to understand how gender differences, for instance, are explained by differential performances on different types or bundles of items, hence differential bundle functioning (DBF). Some previous work has modelled hierarchies in data in this context or considered item responses within persons, but here we model the bundles themselves as explanatory variables at the item level potentially explaining significant intra-class correlation due to gender differences in item difficulty, and thus explaining variation at the second item level. In this study, we analyse DBF using single- and two-level models (the latter modelling random item effects, which models responses at Level 1 and items at Level 2) in a high-stakes National Mathematics test. The models show comparable regression coefficients but the statistical significances of the two-level models are smaller due to the larger values of the estimated standard errors. We discuss the contrasting relevance of this effect for test developers and gender researchers.  相似文献   

3.
This article defines and demonstrates a framework for studying differential item functioning (DIF) and differential test functioning (DTF) for tests that are intended to be multidimensional The procedure introduced here is an extension of unidimensional differential functioning of items and tests (DFIT) recently developed by Raju, van der Linden, & Fleer (1995). To demonstrate the usefulness of these new indexes in a multidimensional IRT setting, two-dimensional data were simulated with known item parameters and known DIF and DTE The DIF and DTF indexes were recovered reasonably well under various distributional differences of Os after multidimensional linking was applied to put the two sets of item parameters on a common scale. Further studies are suggested in the area of DIF/DTF for intentionally multidimensional tests.  相似文献   

4.
The central idea of differential item functioning (DIF) is to examine differences between two groups at the item level while controlling for overall proficiency. This approach is useful for examining hypotheses at a finer-grain level than are permitted by a total test score. The methodology proposed in this paper is also aimed at estimating differences at the item rather than the overall score level, yet with the innovation where item-level differences for many groups simultaneously are the focus. This is a straightforward generalization of DIF as variance rather than one or several group differences; conceptually, this can be referred to as item difficulty variation (IDV). When instruction is of interest, and "groups" is a unit at which instruction is determined or delivered, then IDV signals value-added effects that can be influenced by either demographic or instructional variables.  相似文献   

5.
This paper considers a modification of the DIF procedure SIBTEST for investigating the causes of differential item functioning (DIF). One way in which factors believed to be responsible for DIF can be investigated is by systematically manipulating them across multiple versions of an item using a randomized DIF study (Schmitt, Holland, & Dorans, 1993). In this paper: it is shown that the additivity of the index used for testing DIF in SIBTEST motivates a new extension of the method for statistically testing the effects of DIF factors. Because an important consideration is whether or not a studied DIF factor is consistent in its effects across items, a methodology for testing item x factor interactions is also presented. Using data from the mathematical sections of the Scholastic Assessment Test (SAT), the effects of two potential DIF factors—item format (multiple-choice versus open-ended) and problem type (abstract versus concrete)—are investigated for gender Results suggest a small but statistically significant and consistent effect of item format (favoring males for multiple-choice items) across items, and a larger but less consistent effect due to problem type.  相似文献   

6.
Although the root-mean squared deviation (RMSD) is a popular statistical measure for evaluating country-specific item-level misfit (i.e., differential item functioning [DIF]) in international large-scale assessment, this paper shows that its sensitivity to detect misfit may depend strongly on the proficiency distribution of the considered countries. Specifically, items for which most respondents in a country have a very low (or high) probability of providing a correct answer will rarely be flagged by the RMSD as showing misfit, even if very strong DIF is present. With many international large-scale assessment initiatives moving toward covering a more heterogeneous group of countries, this raises issues for the ability of the RMSD to detect item-level misfit, especially in low-performing countries that are not well-aligned with the overall difficulty level of the test. This may put one at risk of incorrectly assuming measurement invariance to hold, and may also inflate estimated between-country difference in proficiency. The degree to which the RMSD is able to detect DIF in low-performing countries is studied using both an empirical example from PISA 2015 and a simulation study.  相似文献   

7.
This article proposes two multidimensional IRT model-based methods of selecting item bundles (clusters of not necessarily adjacent items chosen according to some organizational principle) suspected of displaying DIF amplification. The approach embodied in these two methods is inspired by Shealy and Stout's (1993a, 1993b) multidimensional model for DIF. Each bundle selected by these methods constitutes a DIF amplification hypothesis. When SIBTEST (Shealy & Stout, 1993b) confirms DIF amplification in selected bundles, differential bundle functioning (DBF) is said to occur. Three real data examples illustrate the two methods for suspect bundle selection. The effectiveness of the methods is argued on statistical grounds. A distinction between benign and adverse DIF is made. The decision whether flagged DIF items or DBF bundles display benign or adverse DIF/DBF must depend in part on nonstatistical construct validity arguments. Conducting DBF analyses using these methods should help in the identification of the causes of DIF/DBF.  相似文献   

8.
This study evaluated the connection between gender differences in examinees' familiarity, interest, and negative emotional reactions to items on the Advanced Placement Psychology Examination and the items' gender differential item functioning (DIF). Gender DIF and gender differences in interest varied appreciably with the content of the items. Gender differences in the three variables were substantially related to the items' gender DIF (e.g., R = .50). Much of the gender DIF on this test may be attributable to gender differences in these variables.  相似文献   

9.
In this study, the effectiveness of detection of differential item functioning (DIF) and testlet DIF using SIBTEST and Poly-SIBTEST were examined in tests composed of testlets. An example using data from a reading comprehension test showed that results from SIBTEST and Poly-SIBTEST were not completely consistent in the detection of DIF and testlet DIF. Results from a simulation study indicated that SIBTEST appeared to maintain type I error control for most conditions, except in some instances in which the magnitude of simulated DIF tended to increase. This same pattern was present for the Poly-SIBTEST results, although Poly-SIBTEST demonstrated markedly less control of type I errors. Type I error control with Poly-SIBTEST was lower for those conditions for which the ability was unmatched to test difficulty. The power results for SIBTEST were not adversely affected, when the size and percent of simulated DIF increased. Although Poly-SIBTEST failed to control type I errors in over 85% of the conditions simulated, in those conditions for which type I error control was maintained, Poly-SIBTEST demonstrated higher power than SIBTEST.  相似文献   

10.
Investigations of differential item functioning (DIF) have been conducted mostly on ability tests and have found little evidence of easily interpretable differences across various demographic subgroups. In this study, we examined the degree to which DIF in biographical data items referencing academically relevant background, experiences, and interests was related to differences in judgments about access to these experiences by members of different gender and race subgroups. DIF in the location parameter was significantly related (r = –.51, p < .01) to gender differences in perceived accessibility to experience. No significant relationships with accessibility were observed for DIF in the slope parameter across gender groups or for the slope and location parameters associated with DIF across Black and White groups. Practical implications for use of biodata and theoretical implications for DIF research are discussed.  相似文献   

11.
In gender differential item functioning (DIF) research it is assumed that all members of a gender group have similar item response patterns and therefore generalizations from group level to subgroup and individual levels can be made accurately. However DIF items do not necessarily disadvantage every member of a gender group to the same degree, indicating existence of heterogeneity of response patterns within gender groups. In this article the impact of heterogeneity within gender groups on DIF investigations was investigated. Specifically, it was examined whether DIF results varied when comparing males versus females, gender × socioeconomic status subgroups and latent classes of gender. DIF analyses were conducted on reading achievement data from the Canadian sample of the Programme of International Student Assessment 2009. Results indicated considerable heterogeneity within males and females and DIF results were found to vary when heterogeneity was taken into account versus when it was not.  相似文献   

12.
Traditional methods for examining differential item functioning (DIF) in polytomously scored test items yield a single item‐level index of DIF and thus provide no information concerning which score levels are implicated in the DIF effect. To address this limitation of DIF methodology, the framework of differential step functioning (DSF) has recently been proposed, whereby measurement invariance is examined within each step underlying the polytomous response variable. The examination of DSF can provide valuable information concerning the nature of the DIF effect (i.e., is the DIF an item‐level effect or an effect isolated to specific score levels), the location of the DIF effect (i.e., precisely which score levels are manifesting the DIF effect), and the potential causes of a DIF effect (i.e., what properties of the item stem or task are potentially biasing). This article presents a didactic overview of the DSF framework and provides specific guidance and recommendations on how DSF can be used to enhance the examination of DIF in polytomous items. An example with real testing data is presented to illustrate the comprehensive information provided by a DSF analysis.  相似文献   

13.
The TOEFL® iBT has increased the length of each reading passage to better approximate academic reading at North American universities, resulting in a reduction in the number of passages on the reading section of the test. One of the concerns brought about by this change is whether the decrease in topic variety increases the likelihood that an examinee's familiarity with the content of a given passage will influence the examinee's reading performance. This study investigated differential item functioning and differential bundle functioning for six TOEFL® iBT reading passages (N?=?8,692), three involving physical science and three involving cultural topics. The majority of items displayed little or no DIF. When all of the items in a passage were examined, none of the passages showed differential functioning at the passage level. Hypotheses are provided for the DIF occurrences. Implications on fairness issues in test development are also discussed.  相似文献   

14.
The assessment of differential item functioning (DIF) in polytomous items addresses between-group differences in measurement properties at the item level, but typically does not inform which score levels may be involved in the DIF effect. The framework of differential step functioning (DSF) addresses this issue by examining between-group differences in the measurement properties at each step underlying the polytomous response variable. The pattern of the DSF effects across the steps of the polytomous response variable can assume several different forms, and the different forms can have different implications for the sensitivity of DIF detection and the final interpretation of the causes of the DIF effect. In this article we propose a taxonomy of DSF forms, establish guidelines for using the form of DSF to help target and guide item content review and item revision, and provide procedural rules for using the frameworks of DSF and DIF in tandem to yield a comprehensive assessment of between-group measurement equivalence in polytomous items.  相似文献   

15.
Gender fairness in testing can be impeded by the presence of differential item functioning (DIF), which potentially causes test bias. In this study, the presence and causes of gender-related DIF were investigated with real data from 800 items answered by 250,000 test takers. DIF was examined using the Mantel–Haenszel and logistic regression procedures. Little DIF was found in the quantitative items and a moderate amount was found in the verbal items. Vocabulary items favored women if sampled from traditionally female domains but generally not vice versa if sampled from male domains. The sentence completion item format in the English reading comprehension subtest favored men regardless of content. The findings, if supported in a cross-validation study, can potentially lead to changes in how vocabulary items are sampled and in the use of the sentence completion format in English reading comprehension, thereby increasing gender fairness in the examined test.  相似文献   

16.
DIF分析实际应用中的常见问题及其研究新进展   总被引：1，自引：0，他引：1  
多等级计分题、小样本、匹配变量不纯以及DIF检验后的原因分析是DIF检验面临的常见问题,对多等级计分题目进行DSF分析,小样本情况下DIF检测的平滑方法,匹配变量不纯情况下采用MIMIC法,以及运用Logistic模型进行DIF检验后的原因分析是DIF研究中的一些新进展。对这些进展的分析使我们相信,多种检验方法的配合使用、运用DIF研究进行多维IRT框架下的潜在变量探究等,都有可能使DIF研究成为测量学未来的基础研究领域之一。  相似文献   

17.
Once a differential item functioning (DIF) item has been identified, little is known about the examinees for whom the item functions differentially. This is because DIF focuses on manifest group characteristics that are associated with it, but do not explain why examinees respond differentially to items. We first analyze item response patterns for gender DIF and then illustrate, through the use of a mixture item response theory (IRT) model, how the manifest characteristic associated with DIF often has a very weak relationship with the latent groups actually being advantaged or disadvantaged by the item(s). Next, we propose an alternative approach to DIF assessment that first uses an exploratory mixture model analysis to define the primary dimension(s) that contribute to DIF, and secondly studies examinee characteristics associated with those dimensions in order to understand the cause(s) of DIF. Comparison of academic characteristics of these examinees across classes reveals some clear differences in manifest characteristics between groups.  相似文献   

18.
Identifying the Causes of DIF in Translated Verbal Items   总被引：1，自引：0，他引：1  
Translated tests are being used increasingly for assessing the knowledge and skills of individuals who speak different languages. There is little research exploring why translated items sometimes function differently across languages. If the sources of differential item functioning (DIF) across languages could be predicted, it could have important implications on test development, scoring and equating. This study focuses on two questions: “Is DIF related to item type?”, “What are the causes of DIF?” The data were taken from the Israeli Psychometric Entrance Test in Hebrew (source) and Russian (translated). The results indicated that 34% of the items functioned differentially across languages. The analogy items were the most problematic with 65% showing DIF, mostly in favor of the Russian-speaking examinees. The sentence completion items were also a problem (45% D1F). The main reasons for DIF were changes in word difficulty, changes in item format, differences in cultural relevance, and changes in content.  相似文献   

19.
The purpose of the present study is to examine the language characteristics of a few states' large-scale assessments of mathematics and science and investigate whether the language demands of the items are associated with the degree of differential item functioning (DIF) for English language learner (ELL) students. A total of 542 items from 11 assessments at Grades 4, 5, 7, and 8 from three states were rated for the linguistic complexity based on a developed linguistic coding scheme. The linguistic ratings were compared to each item's DIF statistics. The results yielded a stronger association between the linguistic rating and DIF statistics for ELL students in the “relatively easy” items than in the “not easy” items. Particularly, general academic vocabulary and the amount of language in an item were found to have the strongest association with the degrees of DIF, particularly for ELL students with low English language proficiency. Furthermore, the items were grouped into four bundles to closely look at the relationship between the varying degrees of language demands and ELL students' performance. Differential bundling functioning (DBF) results indicated that the exhibited DBF was more substantial as the language demands increased. By disentangling linguistic difficulty from content difficulty, the results of the study provide strong evidence of the impact of linguistic complexity on ELL students' performance on tests. The study discusses the implications for the validation of the tests and instructions for ELL students.  相似文献   

20.
One approach to measuring unsigned differential test functioning is to estimate the variance of the differential item functioning (DIF) effect across the items of the test. This article proposes two estimators of the DIF effect variance for tests containing dichotomous and polytomous items. The proposed estimators are direct extensions of the noniterative estimators developed by Camilli and Penfield (1997) for tests composed of dichotomous items. A small simulation study is reported in which the statistical properties of the generalized variance estimators are assessed, and guidelines are proposed for interpreting values of DIF effect variance estimators.  相似文献   

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