A post by Slashdot user Dangerous_Minds summarizes a series ZeroPaid's Drew Wilson, who has been examining 20 file-sharing studies from the decade-plus-long filesharing wars. Time and again, the studies show that the effect on markets is marginal, and that the big entertainment companies are opposed to file-sharing a means of suppressing competition and innovation:

While most writers would simply criticize the study and move on, Wilson took it a step further and looked in to what file-sharing studies have really been saying throughout the years. What he found was an impressive 19 of 20 studies not getting any coverage. He launched a large series detailing what these studies have to say on file-sharing. The first study suggests that file-sharing litigation was a failure. The second study said that p2p has no effect on music sales. The third study found that the RIAA suppresses innovation. The fourth study says that the MPAA has simply been trying to preserve its oligopoly. The fifth study says that even when one uses the methodology of one download means one lost sale, the losses amount to less than $2 per album. The studies, so far, are being posted on a daily basis and are certainly worth the read."