Hey! I think this is a bit of a political issue. My primary sup is on all of my papers as a co-author, since she has commented on many drafts before I've submitted my papers. However, I do have a second supervisor who is much less involved in what I do, and when I have asked my primary sup whether to put him down as last author she always points out that he's had nothing to do with the paper at all. In fairness, he doesn't look at my work unless it's for a PhD review or something, but there is a weird sort of rivalry between my two sups so I don't think she would ever let me put his name down on my papers. Her other reason is 'well, I bet my name won't go down on sup no. 2's students' papers'....so it seems a lot of it is about competition and rivalry. I did wonder if I should ask my second sup if he should go on my empirical papers since he contributed a lot towards recruitment, but if he says yes and my primay sup says no then I won't know what to do! So I don't think there's an obvious or standard answer to your question. At the same time I would tend to err on the side of caution- the last thing you want to do is majorly annoy your sup just for the sake of putting their name on the paper. You could just ask them?!!! KB