I am nearly completing a social science PhD and my supervisor has been requesting my data. I am currently stalling on this, as I know once they get hold of it, it will appear in papers/conference talks and will then reduce my chances of publishing it. I wanted to ask whether anyone else has had this problem? and how they resolved these issues.

Have you any reason to suspect that your supervisor will not acknowledge your contribution if she/he refers to your work at a conference etc? It's quite normal for a supervisor to use a student's work in this way and can be a very positive thing. You should, of course, also be given the chance to present your own work and write your own papers.

Thanks for your reply,
My supervisor has acknowledged my contribution on research papers, but at the end of a list of 6 other researchers. I know from research publications that unless you are first or second author, they become meaningless. Furthermore you have little or no control over the interpretation of the results.

Hmm, the whole order of authors thing is a bit of a contentious issue (mind you, in science, last position tends to indicate head of group!). Can you not discuss your concerns directly with your supervisor? You don't have to be confrontational, you could just raise the issue by telling him/her that you are keen to publish your results and ask for some advice about which journal to target etc. But don't worry about not being able to publish data that has been presented at a conference, that's certainly not a problem.