Comparing the Aberrant Response Detection Performance of Thirty-Six Person-Fit Statistics

The accurate measurement of examinee test performance is critical to educational decision-making, and inaccurate measurement can lead to negative consequences for examinees. Person-fit statistics are important in a psychometric analysis for de-tecting examinees with aberrant response patterns that lead to inaccurate measure-ment. Unfortunately, although a large number of person-fit statistics is available, there is little consensus as to which ones are most useful. The purpose of this study was to compare 36 person-fit indices, under different testing conditions, to obtain a better consensus as to their relative merits. The results of these comparisons, and their implications, are discussed. Sound decisions in educational settings hinge largely on accurate measurement of student characteristics. Such measurements can help identify those individuals who are qualified enough to enter a particular school, or receive a particular edu-cational degree. Also, these measurements can be used to monitor students ’ learn-ing progress. This may, for example, enable educators to productively tailor their curriculum, or help policy makers decide on important educational issues. In contrast, the inaccurate measurement of test performance can lead to nega-tive consequences. On the one hand, spuriously high test scores can lead to un-qualified individuals being enrolled into an educational program (e.g., undergrad-uate, graduate, or professional), or being awarded an educational degree. On the other hand, qualified individuals with spuriously low test scores may be unfairly excluded from academic programs, or unfairly denied a degree. Furthermore, the inaccurate measurement of test performance undermines the assessment of stu-dents ’ learning progress, and curriculum planning efforts.