Sandip Sinharay

Producers and consumers of student assessments are increasingly concerned about fraudulent behavior before and during the test. The United States Government Accountability Office noted that effective test security policies and procedures, when properly implemented, can help prevent and detect cheating and other irregularities that can undermine the validity and reliability of assessments.

The operational analyses in the National Assessment of Educational Progress (NAEP) make heavy use of item response theory (IRT) models. Standard 3.9 of the Standards for Educational and Psychological Testing advocates for evidence of model fit when an IRT model is used to make inferences from a data set. Hence, it is important to assess the fit of the statistical model used by NAEP for quality control purposes and for the long-term, overall improvement of the program.

With the introduction of the No Child Left Behind Act of 2001, the number of tests taken by U.S. grade school students grew. Many of these tests administer different test forms on different dates so that students who take the test on different dates will not answer exactly the same test questions. To ensure fair scores on high-stakes exams, individual differences in scores taken on exams on different test dates must reflect differences in achievement levels of the students and not difference...