Dif rasch analysis pdf

Fourth, rasch analysis can reveal the targeting, which refers to the extent to which items are of appropriate difficulty for the sample. Using differential step functioning analysis and rasch. Rasch analysis of the families in early intervention. Analyzing differential item functioning dif with rasch. If the data form disjoint subsets then, even after collapsing items into superitems, the disjoint subsets will still exist, but dif analysis becomes difficult. Dif estimates with the the iterativelogit raschwelch method. The patientrated wrist evaluation prwe was developed as a wrist joint specific measure of pain and disability and evidence of sound validity has been accumulated through classical psychometric methods. Dif analysis is usually done in an unanchored analysis, because anchoring skews the dif. If there is differential item performance, the difficulty for the reference group dr, will be different from the difficulty for the focus group df.

Using the raschtree function for detecting differential. Analyzing differential item functioning dif with rasch winsteps john. Title irt introduction to irt models descriptionremarks and examplesreferencesalso see description item response theory irt is used in the design, analysis, scoring, and comparison of tests andsimilar instruments whose purpose is to measure unobservable characteristics of. Practice analysis 1 ractice rm 06 calchildren 10 techniques switzerland and chinese bcount etc. Request pdf rasch analysis and differential item functioning of a social support measure in jail inmates with hiv infection the protective effects of social support on health have been. The significance level shows that the difference between the performance of the groups on the item is significant. Detection of uniform differential item functioning dif within the rasch model typically employs null hypothesis testing with a concomitant consideration of effect size e. Recommendations for characterizing dif with meaningful consequences within the rasch model framework article fulltext. This book applies rasch measurement theory to the fields of education, psychology, sociology, marketing and health outcomes in order to measure various social constructs. In standard profile healthstatus instruments, we are dealing with an idealpoint or singlepeaked data structure chapter 5. Irt item response theory data analysis and statistical. This study a provided a conceptual introduction to differential item functioning dif, b introduced the multifaceted rasch rating scale model mrsm and an associated statistical procedure for identifying dif in rating scale items, and c applied this procedure to previously collected data from american coaches who responded to the coaching efficacy. A multidimensional rasch analysis of gender differences in pisa mathematics ou lydia liu educational testing service, princeton mark wilson university of california, berkeley insu paek educational testing service, princeton since the 1970s, much attention has been devoted to the male advantage in standardized mathematics tests in the united states.

Measuring differential item and test functioning across. Rasch trees divide the sample by subjecting the data to recursive nonlinear partitioning. A multidimensional rasch analysis of gender differences in. Of course, mh has the authority of ets and that is decisive in legal situations. To take account of dif in order to retain precision of measurement, split of dif items into separate sample specific items has become a frequently used technique.

Differential item functioning using rasch analysis brodersen j,thorsen h university of copenhagen, copenhagen, denmark objectives. Pdf an introduction to differential item functioning. The item invariance in rasch analysis refers to the independence of estimated item location parameters to the sample in which the estimates are derived from. The chief focus is on first principles of both the theory and its applications. Rasch analysis and differential item functioning of work. Rasch analysis requires a cumulative data structure i. An anovalike rasch analysis of differential item functioning.

Differential item functioning dif, also referred to as item bias, occurs when different groups possess comparable levels of the trait being measured but respond differently to the individual items 10, 21, 22. Rasch analysis software such as winsteps linacre, 2010a calculate dif and offer a significance level. A comparison of uniform dif effect size estimators under. Ad hoc interpretations the next problem pertains to the kind of interpretations offered for the sources of dif. Eric ej1041741 using rasch analysis to examine the. Development of a patientreported palliative carespecific health classification system. 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. Using rasch analysis to validate the motor activity log. The dif differential item functioning or dpf differential person functioning analysis proceeds with all items and persons, except the item or person currently targeted, anchored at the measures from the main analysis estimated from all persons and items, including the currently targeted ones. Differential item functioning dif in composite health measurement scale. The fem was analyzed with the rasch rating scale model rasch, 1980 to obtain linear interval measures. 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. This study uses the rasch model technique to examine the dimensionality structure and differential item functioning of the arabic version of the perceived physical ability scale for children ppasc. A rasch analysis of the integrated palliative care outcome.

Using the rasch measurement model in psychometric analysis. Practical details of this are shown using winsteps output tables. Dif analysis supported a similar probability of endorsing each item category across the gender subgroups as well as the languagecontext subgroups. The rasch model, a member of a larger group of models within item response theory, is widely used in empirical studies. Wang, wenchung the conventional twogroup differential item functioning dif analysis is extended to an analysis of variancelike anovalike dif analysis where multiple factors. A b s t r a c t the present study applied recursive partitioning rasch trees to a largescale reading comprehension test n 1550 to identify sources of dif. Rasch analysis was used to assess unidimensionality, response category functioning, item fit, person reliability, differential item functioning by race and parental status, and item hierarchy. The concept of dif was developed as an alternative to item bias to avoid an implicit negative evaluation of the consequences of an item functioning differently for a group of test takers angoff 1993. Rasch analysis ra has been endorsed as a newer method for analyzing the clinical measurement properties of selfreport outcome measures. The main advantage of the rasch tree approach is that dif can be detected between groups of subjects created by more than one covariate. To take account of dif in order to retain precision of measurement, split of dif items into separate sample specific items has become a.

Rasch analysis of the patientrated wrist evaluation. The aims of this paper are to report on the methodological aspects of dif using rasch analysis and to demonstrate how the mean scores in a scale can be adjusted due to uniform dif. Rasch analysis with a focus on differential item functioning dif is increasingly used for examination of psychometric properties of health outcome measures. A sample of 220 omani fourth graders 120 males and 100 females responded to an arabic translated version of the ppasc. Judicious application of this methodology by the researchers, however, requires an understanding of the technical complexities involved. Differential item functioning dif has been increasingly applied in fairness studies in psychometric circles. Dif is unexpectedly high or low performance by a group of people on a test item, relative to their overall performances. Recommendations for characterizing dif with meaningful consequences within the rasch. In order to detect dif with the raschtree function, the item responses and all covariates that should be tested for dif need to be handed over to the method, as described below.

The aim of the study was to test items for differential item functioning dif in a conditionspeci. Rasch analysis and differential item functioning of a social support measure in jail inmates with hiv infection sage kim, lawrence j. Dif measure is the difficulty of this item for this class, with all else held constant, e. Advantages for a rasch approach to dtf or dif are that the rasch approach allows for missing data and highlow ability groupsplits, but mh does not. Dif estimates with the the iterativelogit rasch welch method. Recent advances in analysis of differential item functioning in health research using the rasch model curt hagquist1 and david andrich2 abstract background. The response forms were adequate, the item difficulty matched respondents ability levels, and we found unidimensionality in the 3 factors. Methodological aspects of differential item functioning in. This is a very important issue because the whole value of dif depends on this phase of the analysis.

Dif analysis indicated that the items did not function differently by child age. A comparison of the polytomous rasch analysis output of. Rasch analysis and differential item functioning of a. Identifying differential item functioning of rating scale. The dif and dtf tests were performed using rasch analysis, which controls for ability across groups, ensuring that items are only flagged if groups of testtakers of the same ability levels exhibit a significantly different probability of endorsing the item. Dif is a statistical concept, while item bias is a social concept. In contrast, nonuniform dif is characterised by an uneven difference in item function across the latent variable measured. The difficulty of each item is then estimated for each group on that common ability scale. Using rasch analysis to examine the dimensionality structure and differential item functioning of the arabic version of the perceived physical ability scale for children sabry m. The results indicated that the scores on the feiqol were reliable and fit the rasch model.