The purpose of this study was to apply two types of Differential Item Functioning (DIF), net and global DIF, as well as the framework of Differential Step Functioning (DSF) to real testing data to investigate measurement invariance related to test language. Data from the Program for International Student Assessment (PISA)-2006 polytomously scored…

Differential item functioning (DIF) can undermine the validity of cross-lingual comparisons. While a lot of efficient statistics for detecting DIF are available, few general findings have been found to explain DIF results. The objective of the article was to study DIF sources by using a mixed method design. The design involves a quantitative phase…

This article investigates the accuracy of examinee classification into performance categories and the estimation of the theta parameter for several item response theory (IRT) scaling techniques when applied to six administrations of a test. Previous research has investigated only two administrations; however, many testing programs equate tests…

In many testing programs it is assumed that the context or position in which an item is administered does not have a differential effect on examinee responses to the item. Violations of this assumption may bias item response theory estimates of item and person parameters. This study examines the potentially biasing effects of item position. A…

This study examined how much improvement was attainable with respect to accuracy of differential item functioning (DIF) measures and DIF detection rates in the Mantel-Haenszel procedure when employing focal and reference groups with notably unbalanced sample sizes where the focal group has a fixed small sample which does not satisfy the minimum…

The purpose of this study was to examine the performance of differential item functioning (DIF) assessment in the presence of a multilevel structure that often underlies data from large-scale testing programs. Analyses were conducted using logistic regression (LR), a popular, flexible, and effective tool for DIF detection. Data were simulated…

The authors studied more than 1 million Asian American and Pacific Islander (AAPI) and White seventh graders in a statewide California testing program between 2003 and 2008, examining their reading and math achievement. AAPI student performance is often reported as an aggregate in discussions of the success of schoolchildren and issues of racial…

The equating process links scores from different editions of the same test. For testing programs that build nearly parallel forms to the same explicit content and statistical specifications and administer forms under the same conditions, the linkings between the forms are expected to be equatings. Score equity assessment (SEA) provides a useful…

This study introduced and demonstrated a new methodology for item and test bias studies: moderated differential item functioning (DIF). This technique expands the DIF methodology to incorporate contextual and sociological variables as moderating effects of the DIF. The study explored differential domain functioning (DDF), so that the focus of…

The differential performance of black and white college freshmen on a direct measure of writing skills, the essay portion of the American College Testing Program's Collegiate Assessment of Academic Proficiency (CAAP), was studied. The data consisted of responses of a sample of 998 black and 3,727 white examinees to two individual prompts for…

The agreement between Mantel-Haenszel and Rasch procedures for identifying differential item functioning (DIF) on teacher certification tests was studied. Two specific research questions were addressed: (1) whether the Mantel-Haenszel and Rasch procedures identify the same items as functioning differently; and (2) how consistently each method…

This study addresses the sample error and linking bias that occur with small and unrepresentative samples in a non-equivalent groups anchor test (NEAT) design. We propose a linking method called the "synthetic function," which is a weighted average of the identity function (the trivial equating function for forms that are known to be…

The Comprehensive Tests of Basic Skills, Form U, is scored in two ways: number-correct and pattern. The latter makes use of the information about which particular items are answered correctly, giving more weight to the more discriminating items and making allowances for guessing. Critics have suggested that black students are penalized by pattern…

The effect of calculator type on student performance on a mathematics examination was studied. Differential item functioning (DIF) methodology was applied to examine group differences (calculator use) on item performance while conditioning on the relevant ability. Other survey questions were developed to ask students the extent to which they used…

Test-item writing efforts typically results in item pools with an undesirable correlational structure between the content attributes of the items and their statistical information. If such pools are used in computerized adaptive testing (CAT), the algorithm may be forced to select items with less than optimal information, that violate the content…