Manipulated factors included the number of groups 10 or 20, magnitude of dif, percent of dif items, the nature of dif, as well as the percent of affected. Differential item functioning detection and effect. An introduction to differential item functioning analysis eric. A general framework and an r package for the detection of. It also compares the effect size measures that these procedures provide. Even though one item in the scale for adolescents and two items in the scale for young adults showed significant dif, the two scales exhibited nonsignificant differential test functioning dtf.
A new method for detecting differential item functioning. If dif is found for many items on the test, the final test scores do not represent the same. 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of the statistics involved in item response theory likelihoodratio tests for differential item functioning, 2001, unpublished manuscript to complete dif analyses. Differential item functioning analysis with ordinal logistic. Evaluates test items for differential item functioning dif. 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. Percentage of low, medium, and highdifficulty items flagged for differential item functioning dif in comparisons involving a nonaccommodated, nondisabled group. Differential item functioning in an irt context, an item with dif has a different category response function crf for one group of people versus another.
Differential item functioning in a brazilian version of the cpq. Piskunov this text is designed as a course of mathematics for higher technical schools. Measurement invariance and differential item functioning. The purpose of dif analyses is to detect response differences of items in questionnaires, rating scales, or tests across different. Background dif occurs in an item when, after controlling for the underlying trait measured by the test, the probability of endorsing the item varies across groups. 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. Differential item functioning dif occurs when items in a measure perform in ways that are different for members of a target group when the different performance is not related to the individuals overall ability to be assessed. A powerful methodology for identifying biased items is the differential item functioning, or dif, study. As a service to our customers we are providing this early version of the manuscript. Dif is a necessary but not sufficient condition for item bias. This simulation study examines item level differential item functioning dif in the context of international largescale assessment ilsa using a generalized logistic regression approach. Recommendations for conducting differential item functioning.
Differential item functioning related to age in the reading. Apr 17, 2006 thanks to kit baum, 4 new programs for detecting differential item function dif and for interfacing with parscale are downloadable from ssc. In general, one of the groups is fixed as the reference group typically it comprises individuals whom the researcher suspects the test favors and the other one is considered the focal group. Eric ej690033 differential item functioning detection and. New programs for differential item function dif and for. 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. If dif is found for many items on the test, the final test scores do. This article provides a brief primer overview of differential item functioning dif analysis. We present an ordinal logistic regression model for identi. Dorans yanxuan qu april 2010 ets rr10 research report. A nonparametric bayesian diagnostic for detecting differential item functioning in irt models mark e. Differential item functioning analysis with ordinal logistic regression techniques difdetect and difwithpar paul k. Longitudinal differential item functioning detection using. Differential item functional analysis by gender and race.
An alternative model often used in health outcomes research is samejimas 5, 6 graded response model grm, a generalization of the 2pl model that permits estimation of multiple b ij parameters per item j from 1 to m. Starting from a framework for classifying dif detection methods and from a comparative overview of the most traditional methods, an r. A new method for detecting differential item functioning in. Because dif analyses are predicated upon examination of a relationship between a grouping variable and item.
The probability of a positive response to an item is modeled as a function of total scores, group, and the interaction between total score and group. A handbook on the theory and methods of differential item functioning dif. This is the webpage for the handbook on differential item functioning. Evaluation of two types of differential item functioning in. Item response theory detects differential item functioning between healthy and ill children in qol measures. Thanks to kit baum, 4 new programs for detecting differential item function dif and for interfacing with parscale are downloadable from ssc.
The textbook is focused on item response theory overall, but discusses differential item functioning and item bias. Differential item functioning magnitude and impact measures. April 2010 the value of the studied item in the matching criterion in differential item functioning dif analysis xuan tan, bihua xiang, neil j. Differential item functioning in mplus 1 differential item functioning in mplus. 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. Measuring differential item and test functioning across. Differential item functioning and health assessment. 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. Ppt differential item functioning in mplus powerpoint. Detecting differential item functioning using generalized. X fits an item response model when x are item scores e. Differential item functioning analysis with ordinal.
This is a pdf file of an unedited manuscript that has been accepted for publication. Several methods have been proposed in recent decades for identifying items that function differently between two or more groups of examinees. Evaluation of two types of differential item functioning. The value of the studied item in the matchin criterion in. Dif detection is a first step in assessing bias in test items. Differential item functioning columbia university mailman. Once an item is identified as functioning differently from one subpopulation to another, understanding why the item is functioning differently between groups may be useful for many audiences. 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. 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. Differential item functioning dif is the preferred psychometric term for what is otherwise known as item bias. A simulation study provided sample size guidance for. For each item, three models with increasing numbers of predictors are used. Directorate of human resources research and evaluation, department of national defense. Starting from a framework for classifying dif detection methods and from a comparative.
Thus, differentially functioning items elicit different. Pdf differential item functioning in a brazilian version. Differential item functioning dif is when a test item favors or hinders a characteristic exhibited by group members of a testtaking population. Item response theory detects differential item functioning. Matching criterion in differential item functioning dif analysis xuan tan bihua xiang neil j. We analyzed 95 cognitive reading items, administered to students in 29 european countries. The results of dif studies can be followed by investigations into the sources of, and. New programs for differential item function dif and. This article compares several procedures in their efficacy for detecting differential item functioning dif. Differential item functioning dif occurs when examinees with the same ability have different probabilities of endorsing an item. Gibbons, phd, lance jolley, ms, and gerald van belle, phd introduction. Free differential geometry books download ebooks online. From kocklawvere axiom to microlinear spaces, vector bundles,connections, affine space, differential forms, axiomatic structure of the real line, coordinates and formal manifolds, riemannian structure, welladapted topos models. T1 detecting differential item functioning with confirmatory factor analysis and item response theory.
Local dependence was tested using the q3 44 statistic and differential item functioning dif 45. Grm item fit, measurement invariance absence of differential item functioning dif due to age, gender, center, duration, and location of. Differential item functioning dif occurs when people from different groups e. Di erential item functioning patricia martinkova department of statistical modelling institute of computer science, czech academy of sciences nmst 570, december 12, 2017 december 12, 2017 126. When items function differently for different populations, it is referred to as dif. 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. For the focal group, item functioning is compared with that of the reference group. We identified 29 of the 48 items as displaying dif, meaning women and students of color were either more likely or less likely to agree with their caucasian male peers on certain items. Differential item functional analysis by gender and race of. Differential item functioning related to age in the. 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. Differential item functioning dif is an important issue of interest in psychometrics and educational measurement.
Differential item functioning dif, as an assessment tool, has been widely used in quantitative psychology, educational measurement, business management, and insurance and healthcare industries. Lines show the power to detect uniform dif for each combination of number of items, sample size, and fes number added to. Longitudinal differential item functioning detection using bifactor models and the wald test by mian wang a dissertation submitted to the graduate degree program in the department of psychology and the graduate faculty of the university of kansas in partial fulfillment of the requirements for the degree of doctor of philosophy. Paper 29002015 multiple ways to detect differential item.
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. As demonstration, a dataset from a 40item math test in a statewide testing program is analyzed. This procedure comes from the definition of frederic lord on dif then called. Sep 01, 2017 this is the webpage for the handbook on differential item functioning. Current problems and future directions hossein karami, university of tehran, iran mohammad ali salmani nodoushan, iecf, iran. With the rising concerns over the fairness of language tests, differential item functioning dif has been increasingly applied in bias analysis. 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. Differential item functioning magnitude and impact. 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. Lines show the power to detect uniform dif for each combination of number of items, sample size, and fes number added to all b parameters.
The rows in each group refer to the levels from lower to higher, with the fourth row indicating the sum of each ability level. It contains many worked examples that illustrate the theoretical material and serve as models for solving problems. 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. Differential item functioning in the beck depression inventory. An explanatory differential item functioning dif model. Logistic regression modeling as a unitary framework for binary and likerttype ordinal item scores. Detecting differential item functioning with confirmatory. Does differential item functioning occur across respondents. In other words, even when members of two different groups are matched on the latent variable, their probability of giving the same response to the item is not the same. Percentage of low, medium, and highdifficulty items flagged for differential item functioning dif when groups were tested under the same conditions 11 figure 3.16 431 604 134 291 1139 587 1477 1329 776 912 499 570 1073 393 802 467 589 1237 865 1147 632 1303 827 880 724 311 269 499 495 425 952