> We looked at users who copied all or part of any answer, or users who took any voting action (upvote, downvote, etc.) on any answer.

Huh, I probably should have realized it, but the idea that Stack Overflow was tracking whether I copy an answer had never occurred to me.

(Mostly joking, I hope: I guess they could monitize that info for Stack Overflow Jobs, by certifying that a candidate has a low rate of copying answers!)