1. Your Graduate School may randomly check theses and dissertations using Turnitin.
2. “I am not a crook [a cheat]”, “I was taught to do it this way.” Many students do know the rules about plagiarism. But some do not. Others bring practices from professional and governmental work to university, where they are not acceptable.
3. “I have a 4.0 GPA” This may well mean that none of their previous instructors discovered their violations of academic integrity. Hence, such a claim, when the work in front of you is inadequate, may well be a sign of undetected past violations.
4. University regulations require that we report violations to the appropriate committee. In part this is educational, in part it is to prevent future violations. Penalties are still in the faculty member’s hands.
5. Mosaic plagiarism is rife. Namely, a passage from a work is quoted verbatim with a change of one or two words, a reference may be given, but no quotation marks.
6. Paraphrase demands a reference. Turnitin finds paraphrase since some unacknowledged copying of part of the passage is likely.
7. Turnitin is effective in finding problems. You can indicate you don’t want to count stuff in quotation marks, or similar passages less than N words. You still need to examine the paper since indented quoted passages are counted as similar although indentation indicates quotation and should not be counted in the similarity score.
8. Students may well threaten to petition to have a grade change, to get you dismissed, to accuse you of other violations. They are not bad at browbeating. My counsel is to send it to the university committee immediately and let them deal with it.