Research Article
Implementation of the Omega (ω) Index to Detect Large-Scale Systematic Cheating

Alvin Vista

APA 7th edition
Vista, A. (2019). Implementation Of The Omega (ω) Index To Detect Large-Scale Systematic Cheating. European Journal of Educational Research, 8(4), 1307-1322.

Vista A. 2019 'Implementation Of The Omega (ω) Index To Detect Large-Scale Systematic Cheating', European Journal of Educational Research, 8(4), pp. 1307-1322.
Chicago 16th edition
Vista Alvin. "Implementation Of The Omega (ω) Index To Detect Large-Scale Systematic Cheating," European Journal of Educational Research 8, no. 4 (2019): 1307-1322.


Cheating detection is an important issue in standardized testing, especially in large-scale settings. Statistical approaches are often computationally intensive and require specialised software to conduct. We present a two-stage approach that quickly filters suspected groups using statistical testing on an IRT-based answer-copying index. We also present an approach to mitigate data contamination and improve the performance of the index. The computation of the index was implemented through a modified version of an open source R package, thus enabling wider access to the method. Using data from PIRLS 2011 (N=64,232) we conduct a simulation to demonstrate our approach. Type I error was well-controlled and no control group was falsely flagged for cheating, while 16 (combined n=12,569) of the 18 (combined n=14,149) simulated groups were detected. Implications for system-level cheating detection and further improvements of the approach were discussed.

Keywords: Answer-copying indices, item response theory, PIRLS, cheating detection, standardized testing, test integrity.


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