We develop a simple algorithm for detecting exam cheating between students who copy off one another’s exam. When this algorithm is applied to exams in a general science course at a top university, we find strong evidence of cheating by at least 10 percent of the students. Students studying together cannot explain our findings. Matching incorrect answers prove to be a stronger indicator of cheating than matching correct answers. When seating locations are randomly assigned, and monitoring is increased, cheating virtually disappears.
That is Steve Levitt and Ming-Jen Lin in an NBER working paper. Unfortunately it is gated and I do not see an ungated one online (pointers welcome).
I once caught my students doing this, and the university fumbled the investigation and disciplinary situation so badly (eventually taking no action) I can only assume the administration botched it intentionally. (I will not name universities but it can only be one of four.) In any case, the constraint on reducing cheating may not be detection technology.