Cash Acrey has found an excellent way of discouraging students from bringing their classmates clickers to class to answer for them or asking a classmate to do the same for them.
“I periodically take a head-count while the students are answering their first question of the day. Should the number of responses exceed my count, I require the students to manually sign in, which exposes the students who are not actually in class but have a response entered. Doing this early enough in the semester to set a precedent tends to cut those violations out. In fact, I think telling the students on Day 1 that I will be doing this probably mitigates most of it (but they do need to see it in action).” – Cash Acrey
For other ideas on preventing academic integrity violations with clickers, please see our Clickers and Academic Integrity article.