Tschmuck's paper is what he calls a typology: classifying studies by type It is very thorough and my brief summary below doesn't do it justice. He starts by summarizing Liebowitz's theoretical work. The summary seemed adequate.
Next he addresses Bayaan's work, employing game theory concluding that legal methods to fight file-sharing makes people worse off.
Curien/Moreau are next urging that piracy is better for consumers to offset monopoly power and that artists make money from tours.
Peitz et al: talk about sampling benefits of file sharing. [Liebowitz has his work cut out for him.]
Tschmuck argues that the theoretical models of oligopoly and monopolistic competition need to be improved.
Next he addressed survey-based studies, beginning again with Liebowitz's work showing that file-sharing led to a decline in music sales.
Boorstein used survey data, too, and criticized Liebowitz's work, but Liebowitz extended the data and Boorstein's results were reversed!
Zentner: file-sharing reduces the probability of sales by as much as 30%. used tonnes of European data. Concludes a likely reduction in sales was actually 7.8%
Chi: says she found a positive, not negative effect, but it was questionable [Tschmuck's tone revealed his skepticism].
Andersen/Frenz found a positive effect, too.
A Dutch study found that P2P file sharing eroded the profitability of album sales but boosted the profitability of concerts. [seems obvious to me. Note: This is at best a 2nd best result.]
Tschmuck's comments on this section seem reasonable for the most part.
Survey data of users
Bounie et al: explorers who sample vs. pirates who don't buy. Nothing clear.
Rob and Waldfogel: downloaders buy less but that increases consumer welfare.
Lee: a price study of price elasticities of demand
Leung: found negative impact on music downloads when punishment for illegal file-sharing is more severe.
Huygen et al: again found that file-sharing reduces record sales but said it is more than offset by concerts and merchandise sales. [if so, then record companies and artists should not be fighting file-sharing; the fact that they are makes me skeptical of these approaches]
Oops I missed a couple here.
Hong: says Napster might have led to a 20% drop in sales to young people (a huge segment of the market).
similar results from Peitz et al.
Tanaka found no effect on CD sales in Japan. Used instrumental variables [ugh].
Bhattacharjee: concluded file-sharing had no impact on chart survival. [so?]
Blackburn: well-known artists suffer from file-sharing. Less well-known don't.
O-G/Strumpf: no effect of file-sharing on sales. Used instrumental variables very questionably.
Overall, a reasonable summary with a great list of references.