I linked to that study, as well as others in
this thread. Like I said there, every independent study I'm aware of concludes that pirates have either little, none or a positive impact on sales. This, of course, in relation to music, where all the research effort into piracy has so far been targeted. Those studies which have included buying habits in their remit have also concluded that pirates buy more music than non-pirates, simply because they are exposed to more and different kinds of music.
All studies funded by MPAA, IFPI, etc. of course conclude otherwise, but that is to be expected. Personally I make it a point to ignore all "research" funded by an interested party, whatever the area, as I consider it inherently untrustworthy. Independent research or bust.