The Impact of Cheating on Score Comparability via Pool-Based IRT Pre-equating

For any testing programs that administer multiple forms across multiple years, maintaining score comparability via equating is essential. With continuous testing and high-stakes results, especially with less secure online administrations, testing programs must consider the potential for cheating on their exams. This study used empirical and simulated data to examine the impact of item exposure and prior knowledge on the estimation of item difficulty and test taker's ability via pool-based IRT preequating. Raw-to-theta transformations were derived from two groups of test takers with and without possible prior knowledge of exposed items, and these were compared to a criterion raw to theta transformation. Results indicated that item exposure has a large impact on item difficulty, not only altering the difficulty of exposed items, but also altering the difficulty of unexposed items. Item exposure makes test takers with prior knowledge appear more able. Further, theta estimation bias for test takers without prior knowledge increases when more test takers with possible prior knowledge are in the calibration population. Score inflation occurs for test takers with and without prior knowledge, especially for those with lower abilities.