Investigating Student Plagiarism Patterns and Correlations to Grades

We analyzed 6 semesters of data from a large enrollment data structures course to identify instances of plagiarism in 4 assignments. We find that the majority of the identified plagiarism instances involve cross-semester cheating and are performed by students for whom the plagiarism is an isolated event (in the studied assignments). Second, we find that providing students an opportunity to work with a partner doesn't decrease the incidence of plagiarism. Third, while plagiarism on a given assignment is correlated with better than average scores on that assignment, plagiarism is negatively correlated with final grades in both the course that the plagiarism occurred and in a subsequent related course. Finally, we briefly describe the Algae open-source suite of plagiarism detectors and characterize the kinds of obfuscation that students apply to their plagiarized submissions and observe that no single algorithm appears to be sufficient to detect all of the cases.