Patterns of plagiarism

We used a new technique to analyse how students plagiarise programs in an introductory programming course. This involved placing a watermark on a student's program and monitoring programs for the watermark during assignment submission. We obtained and analysed extensive and objective data on student plagiarising behaviour. In contrast to the standard plagiarism detection approaches based on pair comparison, the watermark based approach allows us to distinguish between the supplier and the recipient of the code. This gives us additional insight into student behaviour. We found that the dishonest students did not perform significantly worse than the honest students in the exams. However, when dishonest students are further classified into supplier and recipient, it emerged that the recipient students performed significantly worse than the suppliers.