Some difficulties arise due to the large amount of missing responses, which can be avoided by the use of fixed item parameter calibration fipc. Differential item functioning magnitude and impact measures. The use of new item formats, new item types, and new test. This study aimed to examine whether the items of the quality of life enjoyment and satisfaction. Naep analysis and scaling differential item functioning. Differential item functioning analysis with ordinal logistic regression techniques difdetect and difwithpar paul k. An explanatory differential item functioning dif model.
If dif is found for many items on the test, the final test scores do not represent the same. Using restricted factor analysis to select anchor items and detect. As part of its standard operations, ets conducts dif analyses on thousands of items per year. Difd program crane et al, 2004 nonuniform and uniform dif. Differential item functioning dif in composite health. Differential item functioning procedures for polytomous items when examinee sample sizes are small.
This research provides an example of testing for differential item functioning. The analysis of the differential functioning of the item was performed with the use of the technique known as item response theory loglikelihood ratio irtlr, version 2. When items function differently for different populations, it is referred to as dif. If the factor bringing about such a difference is not part of the construct of focus in the test, then the test would be biased. Mplus technical support will be available during this time. Differential item functioning dif is an important issue of interest in psychometrics and educational measurement. A variety of statistical procedures have been developed to assess dif in tests of dichotomous hills, 1989. Assessing differential item functioning among multiple groups. The multipleindicator multiplecause mimic model was utilized to assess differential item functioning dif, comparing english versus french and versus dutch patient responses separately. We present an ordinal logistic regression model for identi. Paper 29002015 multiple ways to detect differential item. The results of dif studies can be followed by investigations into the sources of, and.
This article provides a brief primer overview of differential item functioning dif analysis. Selecting an optimal measurement model and detecting. Differential item functioning dif is investigated to ensure that each item displays a consistent pattern of responses irrespective of the characteristics of the respondents. Differential item functioning columbia university mailman. Recommendations for conducting differential item functioning. This procedure comes from the definition of frederic lord on dif then called. Although mplus is currently the only commercial software that allows for. Judicious application of this methodology by the researchers, however, requires an. Differential test functioning differential test functioning dtf is present when individuals who have the same standing on the latent construct or attribute, but belong to different groups, obtain different scores on the test the presence of dif may lead to dtf, but not always some dif items favour the focal group, whereas others. Potential sources of differential item functioning in the. Current issues 951 people who answered the item correctly at the ability level m, and the proportion of people who answered the item correctly at the ability level m, respectively. Differential item functioning dif in these tests due to cultural and. Differential item functioning dif occurs when people from different groups e.
The item responses of 432 filipino and 610 american college students were analyzed. Detecting differential item functioning with confirmatory. Assessing and adjusting for crosscultural validity of impairment and activity limitation scales through differential item functioning within the framework of the rasch model. Item characteristic curves in the reference and focal groups and differential item functioning dif effectsize used in the simulation model for the four kinds of dif. Differential item functioning magnitude and impact. Measurement invariance mi in cfa and differential item.
Differential item functioning of the sf12 in a populationbased. Assessment developers design and construct questionnaires or tests including sets of items that measure, for example, cognition, personality traits, or political views. New programs for differential item function dif and. Differential item functioning dif analysis is a key component in the evaluation of the fairness and validity of educational tests. All analyses were conducted using mplus software, version 8. Dif is a necessary but not sufficient condition for item bias. Identification of differential item functioning in. Dif detection is a first step in assessing bias in test items. Introduction essentially the same differential item functioning dif procedures have been used in practice since the late 1980s. Evaluates test items for differential item functioning dif. Three methods for detecting differential item functioning diftwo based on item response theory plus the mantelhaenszel method showed fairly good agreement in the detection of dif items. A unidimensional factor model showed good fit in all samples.
Figure 1 displays a scatterplot for the males and females item difficulties. Differential item functioning dif analysis refers to procedures that assess whether items are differentially difficult for different groups of examinees. Differential item functioning in mplus 1 differential item functioning in mplus. Multiple ways to detect differential item functioning in sas. I am helping examine differential item functioning between men and. The assessment of differential item functioning dif has become an integral part of determining the validity of standardized tests and multi item surveys. Pdf an introduction to differential item functioning. This study focuses on the use of multipleindicator multiplecause mimic structural equation models for dif. Differential item functioning dif may be defined as an item that displays different statistical properties for different groups after the groups are matched on an ability measure. Differential item functioning dif of sf12 and qlesqsf. Thanks to kit baum, 4 new programs for detecting differential item function dif and for interfacing with parscale are downloadable from ssc. The differential item functioning analysis software penfield, 2005 and the easydif software gonz alez et al.
Table 30 supports the investigation of item bias, differential item functioning dif, i. However, differential item functioning dif may affect the accurate. Differential item functioning dif, or item bias, occurs when individuals in a focal group respond differently to a test item than do individuals in a reference group even when comparisons are restricted to individuals with similar overall skill levels on the trait in question. Phd doctor of philosophy thesis, university of iowa, 2011. Dif analyses are statistical procedures used to determine to what extent the content of an item affects the item endorsement of subgroups of testtakers.
Item response theory detects differential item functioning. Using mimic methods to detect and identify sources of dif among. A tutorial on structural equation modeling for analysis of. This article provides an applied example using sibtest statistical software to detect dif in u. Quizlet flashcards, activities and games help you improve your grades. An introduction to differential item functioning analysis eric. Identification of differential item functioning in assessment booklet designs with structurally missing data joshua t. Psychometric software is software that is used for psychometric analysis of data from tests, questionnaires, or inventories reflecting latent psychoeducational variables while some psychometric analyses can be performed with standard statistical software like spss, most analyses require specialized to. Thus, differentially functioning items elicit different. Differential item functioning dif is said to occur when the. A differential item functioning analysis of the eq5d in. Differential item functioning between ethnic groups in the epidemiological assessment of depression. Measurement invariance and differential item functioning.
A handbook on the theory and methods of differential item functioning dif. Difas is a windows based program that performs a variety of functions related to assessing the presence of differential item functioning dif in items, differential test functioning dtf across all items of a test or scale, and differential step functioning dsf for ordinal polytomous items. Software for the computation of the statistics involved in item response theory likelihoodratio tests for differential item functioning software program. Identifying cultural differences in items and traits. The mh dif method was conducted using the differential item functioning analysis system difas computer program penfield, 2005. Pretest items are calibrated, and possible differential item functioning dif is analyzed. As is commonly done, the total score was used as the matching. Measurement invariance concerns how the indicators measure the latent trait across groups or timecondition an invariant measurement model has the same factor loadings, item interceptsthresholds, and residual variances and covariances measurement model invariance is a precursor to any group or. In the context of tests, dif occurs when people from different groups with the same ability have systematically different responses to speci. Dif analysis investigates a differential characteristic of a test item between subpopulations of examinees and is useful in detecting possibly biased items toward a particular subpopulation. Average item scores for subgroups having the same overall score on the test are compared to determine whether the item is measuring in essentially the. In this article, the authors developed a common strategy for identifying differential item functioning dif items that can be implemented in both the mean and covariance structures method macs and item response theory irt. Software for the computation of the statistics involved in item response theory likelihoodratio tests for differential item functioning, 2001, unpublished manuscript to complete dif analyses.
Measuring differential item and test functioning across. As a result, the differential item functioning analysis system difas was developed to provide a costeffective and easytouse program for conducting many of the common nonparametric dif detection procedures, as well as several new dif detection procedures that are not available in other statistical packages. This is the webpage for the handbook on differential item functioning. Differential item functioning analysis with ordinal. Differential item functioning dif has been widely used in healthcare, business management, and educational measurement. A handbook on the theory and methods of differential item functioning dif logistic regression modeling as a unitary framework for binary and likerttype ordinal item scores bruno d. Dif occurs when examinees from different groups show differing probabilities of success on or endorsing the item after matching on the construct that the item is intended to measure notice that this is exactly the definition of mi applied to test items. An important feature of the mimic model given our analyses of overlapping symptoms, is that it permits detection and adjustment for differential item functioning dif. Chapter 5 study guide by kristilee includes 26 questions covering vocabulary, terms and more. Recent differential item functioning dif analyses have found that many items on. Differential item functioning dif is the preferred psychometric term for what is otherwise known as item bias. Differential item functioning dif has been increasingly applied in fairness studies in psychometric circles. The comparability of english, french and dutch scores on the. Differential item functioning procedures for polytomous.
As demonstration, a dataset from a 40 item math test in a statewide testing program is analyzed. A consequence of having a dif item is that the same true trait levels for examinees from different subpopulations could indicate different total test. In the presence of differential item functioning dif, observed. The purpose of the present analysis is to use differential item functioning dif to identify differences in the performance of native and immigrant students in pisa 2009 that can be directly related to their responses to particular items. Gibbons, phd, lance jolley, ms, and gerald van belle, phd introduction. Differential item functioning, measurement invariance, item bias, confirmatory factor. A powerful methodology for identifying biased items is the differential item functioning, or dif, study. Differential item functioning dif is a statistical characteristic of an item that shows the extent to which the item might be measuring different abilities for members of separate subgroups. The rows in each group refer to the levels from lower to higher, with the fourth row indicating the sum of each ability level. Differential item functioning dif is when a test item favors or hinders a characteristic exhibited by group members of a testtaking population.
Proceedings of sas global forum 2015 conference, dallas, tx, apr 2629, 2015, p19. Average item scores for subgroups having the same overall score on the test are compared to determine whether the item is measuring in essentially the same way for all subgroups. Differential item functioning in malaysian generic skills. Illustration of mimicmodel dif testing with the schedule for. All analyses were carried out using mplus version 4. Empirical studies on differential item functioning 36 research in dikereniial liem fmciioning 36 methods of detecting differential item functioning 3 9 meinojs ihai examine dikerencr, in item d.
Some of these procedures, such as the mantelhaenszel chi. Apr 12, 20 differential item functioning dif is when a test item favors or hinders a characteristic exhibited by group members of a testtaking population. Selecting an optimal measurement model and detecting differential item functioning using bayesian confirmatory factor analysis part i. Differential item functioning dif is present for a test item when respondents from two subpopulations with the same trait level have different probability of answering the item correctly. Assessing dif helps to understand the nature of instruments, to assess the quality of a measure and to interpret results. Here we refer to dif in the classic, irt sense where people from different groups e. Package difr may, 2020 type package title collection of methods to detect dichotomous differential item functioning dif version 5. We analyzed 95 cognitive reading items, administered to students in 29 european countries. Differential item functioning dif occurs when an item on a test or ques tionnaire has different measurement properties for one group of people versus another, irrespective of mean differences on the construct. Chisquare difference tests for detecting differential. Differential item functioning in the beck depression inventory. Several methods have been proposed in recent decades for identifying items that function differently between two or more groups of examinees. Sep 01, 2017 this is the webpage for the handbook on differential item functioning.
An item displays dif when test takers possessing the same amount of an ability or trait, but belonging to different subgroups, do not share the same likelihood of correctly answering the item. The analytic procedure used here was implemented with mplus software, v. Item response theory detects differential item functioning between healthy and ill children in qol measures michelle m. The mplus offices will be closed march 24, 2020 through march 30, 2020. Differential item functioning of the full and brief.
Ppt differential item functioning in mplus powerpoint. Logistic regression modeling as a unitary framework for binary and likerttype ordinal item scores. A general framework and an r package for the detection of. Differential item functioning dif occurs when an item on a test or questionnaire has different measurement properties for 1 group of people versus another, irrespective of mean differences on the construct. For instance, with binary data, dif exists when there is a difference in the conditional probabilities of a correct response for two manifest groups. Klaric educational and psychological measurement 2011 71. The assessment of differential item functioning dif has become an integral part of determining the validity of standardized tests and multiitem surveys. Good software is available for estimating the models with methods designed. In brief, differential item functioning dif occurs when groups such as defined by gender, ethnicity, age, or education have different probabilities of endorsing a given item on a multiitem scale after controlling for overall scale scores. A comparison of item response theorybased methods for examining.