Can we stay one step ahead of cheaters? A field experiment in proctoring online open book exams

•Online assessments are increasing as more courses move to remote learning environments.•Numerous online proctoring solutions have been developed over the past decade.•A field experiment is used to analyze the effects of two proctoring methods on exam scores.•Average scores on non-proctored exams were over 11% higher than on proctored exams.•The effect of web-based proctors is found to be smaller than live in-person proctors.•The marginal effect of proctoring is stronger among lower ability students.