A scientific study on conspiracists? Seems pointless to me. The scientific community, who tend to
not be conspiracists will say, "ah, good data". The conspirasists will say, "it's a conspiracy!!!". And those inbetween are probably not all that familiar or interested in the whole "conspiracy versus science" debate.
Anyway, I think CT's exist because of our need to be able to explaine the world arround us. That (at least, to me) seems to be an inate human quality; curiousness about our environment. And if you lack the learning or skills to be able to explaine the world around you, then you'll be more likely to jump on the easier path to CT'dom.
Therefore, if more people were more learned on science, or at least just scientific method (which applies to all aspects of reason), then you wouldn't see as many CT's. Hmmmm...could probably test that by looking at groups who recieve more formal education in science and reasoning and compair them to groups with less formal education.
Anyway that's my two-cents.