CS PhD students, is it normal to be afraid of false positives in MOSS?

In my MS program, I noticed that assignment averages are unusually high. For that reason, my program institutes a zero tolerance policy on cheating, where if MOSS finds matching code, even if you copy a 3 line routine from stack overflow that carries out a function that is non-critical to the operation of your program, you will have the same punishment as the student who copied all of the code from last semester.

First, I think you've a little misconception. Moss compares files. Obviously (almost?) every conceivable line of code has been written already. Unless your classmates all wrote the same 3 line subroutine, you aren't going to be dinged for it.

Second, you're right, this isn't how MOSS is supposed to be used. Here's Moss' page: https://theory.stanford.edu/~aiken/moss/.

Moss is not a system for completely automatically detecting plagiarism. Plagiarism is a satement that someone copied code deliberately without attribution, and while Moss automatically detects program similarity, it has no way of knowing why codes are similar. It is still up to a human to go and look at the parts of the code that Moss highlights and make a decision about whether there is plagiarism or not. One way of thinking about what Moss provides is that it saves teachers and teaching staff a lot of time by pointing out the parts of programs that are worth a more detailed examination.

Either your understanding of the faculty's usage of MOSS is wrong or you need to have a serious conversation with the dean, professors, etc. Something's very fishy about this story but I don't have enough information.

/r/compsci Thread