“Catching Cheating Students”, Ming-Jen Lin, Steven D. Levitt2019-12-29 (; similar)⁠:

We develop a simple algorithm for detecting exam cheating between students who copy off one another’s exams.

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% of the students. Students studying together cannot explain our findings. Matching incorrect answers proves to be a stronger indicator of cheating than matching correct answers.

When seating locations are randomly assigned, and monitoring is increased, cheating virtually disappears.