Are online exams an invitation to cheat?

In this study, the authors use data from two online courses in principles of economics to estimate a model that predicts exam scores from independent variables of student characteristies. In one course, the final exam was proctored, and in the other course, the final exam was not proctored. In both courses, the first three exams were unproctored. If no cheating took place, the authors expected the prediction model to have the same explanatory power for all exams, and, conversely, if cheating occurred in the unproctored exam, the explanatory power would be lower. Their findings are that both across and within class, variations in the R-squared statistic suggest that cheating was taking place when the exams were not proctored.