Source Torrentfreak:

Commissioned by the Dutch government, a recently published report concludes that file-sharing has a positive effect on the economy, both on the long and short term. A massive 30% of the Dutch population uses file-sharing software to download music, games, movies and other forms of entertainment, which is now considered to be a ‘good thing’.
....
File-sharing gives people access to a wide range of cultural goods and is often used to sample content that is bought later, the report concluded. Most file-sharers would have never bought the content they downloaded, but having access to such a large media library increases the welfare of Dutch citizens, the researchers note.

Frankly, the findings of this study do not surprise me and they point to the power of the long tail for cultural economy. Wider range of access to cultural product is a good thing, in and off itself. People will be able to find what they really care for (rather than stick to what is just not objectionable enough to switch off -- the basic mode of operation of TV and other broadcast media) and form that engagement, many things can flow.

Ars Technica writes:

Things get really interesting on page 116 as the report starts to dissect the societal effects of file sharing. The study concludes that the effects are strongly positive because consumers get to enjoy desirable content and also get to keep their cash to buy other things. Because the consumers save much more money than the producers lose, the net economic effects are positive. The report also reinforces the truth that unpaid downloads do not translate into lost sales in anything close to a one-to-one ratio.