Sources of the differential item functioning and its application in education

Psychometric properties such as measurement inaccuracies, lack of differential action of the question, or lack of bias must be maintained so that the grades of a test can be compared to the different groups of the subject. The analysis of source of differential item functioning allows researchers to formulate hypotheses related to the main and potential sources of bias and the variance of the intruder structure. Since the hypotheses of DIF sources are usually built on the basis of previous theory or research and are discussed in the next step, a systematic review of the papers related to the study of the causes of DIF seems to be necessary. The findings show that the main importance of identifying DIF resources in constructing and interpreting test results is used for comparison between groups. This research is a systematic review that searches for keywords on valid databases such as Taylor & Francis, WILEY, Springer, SAGE. Of the 42 articles found, 19 related articles were identified based on entry criteria. In using each article, we tried to extract the scores in DIF, sources identified for DIF, how to identify the DIF source, the strategy used to impact the identified DIF source.

The findings show that the main importance of identifying sources of DIF in constructing and interpreting test results is used for comparison between groups. DIF happens when we compare certain groups. Policy makers should be careful about the comparability of scores when deciding on curriculum, resources or training based on comparing test scores.