Yesterday I asked on twitter whether or not people had a written "expectations" document in their lab. What I had in mind was much like this "lab philosophy" page that was pointed out by Dr. Becca. If you have a second to go read it, I think you'll find it's worth it.
The response was pretty variable, but more people than I expected answered yes. I don't mean to strictly formalize things in the lab with memos for everything, but I can see how such a document puts everyone on the same page. One could argue that a conversation will do the same, but the document is consistent across anyone who comes into the lab. Additionally, it lets people at different levels get a better feel for what is expected of others.
So, readers, do you have such a document in your lab (as PI or trainee)? If so, do you think it helps? If not, do you think it would help?