When should a supervisor be an author? I understand that in a lot of big-lab fields it is common for the principal investigator to append their name to a paper even if they did not write the paper, design the experiment, or collect data since they spend energy securing funding, and managing the whole lab. What about for small labs?

What are the requirements for a supervisor to be included as an author on a paper, as opposed to just appearing in the acknowledgements? If you are working on your own projects independently of your supervisor, but using funding provided by your supervisor (how does this change when the funding provides resources versus just your salary), are you suppose to add them as authors or just acknowledge the source of funding?
Allow me to strongly disagree with eykanal's answer.  There is no universal standard.  You must ask your advisor in advance what her coauthorship policy is.

In theoretical computer science (and mathematics), it is generally considered unethical to list someone as a co-author who has not made a novel and significant intellectual contribution to the paper.  In particular, merely funding the research is not considered an intellectual contribution.  Adding a supervisor's name to a paper to which they have not directly, intellectually contributed is lying.

In practice, writing a good grant proposal requires at least as much intellectual novelty as writing a good paper.  Most of the good ideas that PIs pour into their proposals also appear in papers; as long as those ideas constitute novel intellectual contributions, the PI merits co-authorship.  But that only works once per idea; once an idea has been published, it's no longer novel, by definition.

To be specific and personal:


I am not a coauthor on all of my PhD students' papers.  (Of course, I still report my students' independent work back to NSF as outcomes on whatever grants supported them.  So I still get credit from NSF for having the foresight to fund the student.)  The same is true of all the other theoretical computer science faculty in my department.
My PhD advisor is a co-author on only one of the papers I published as a PhD student.
My PhD advisor doesn't have a single co-authored paper with his advisor.