A Comparison of Software Tools for Plagiarism Detection in Programming Assignments

摘要

Computing education usually involves intensive practical training through laboratory exercises, programming projects, and homework assignments. Those assignments are frequent targets for plagiarism. In this paper, we discuss social and educational aspects of the source code plagiarism in academic environment, and present an overview of software tools for source code similarity detection. We present our experiences with JPlag, Moss, and SPD tools, and compare them using simulated plagiarism based on programming assignment solutions produced after 1, 2, 4, and 8 hours of work on baseline version using more than 20 types of lexical and structural modifications that students use to hide plagiarism. We also compare results of the selected tools used on real-life student programming solutions from three different courses. The courses were attended by 100 to 300 students, and the programming assignment solutions varied in size and complexity from 50 to 1000 lines of source code. The results show that 5-10% of students plagiarized their solutions. In our experience, JPlag and Moss proved to be effective tools for plagiarism detection, as they clearly indicated cases of similarity which were manually confirmed by human code inspection.