Internet piracy and book sales: a field experiment

The widespread Internet ``piracy'' continues to fuel the debate about business models impervious to copyright infringement. We studied the displacement effects of ``piracy'' on sales in the book industry. We conducted a year-long large-scale field experiment: in the treatment group, we removed unauthorized copies appearing on the Internet and observed the sales data, whereas in the control group, we simply observed sales. We were able to substantially curb the unauthorized distribution, which resulted in a small, positive effect on sales. While using classical analysis we found it not to be significantly different from zero, a Bayesian approach using previous ``piracy'' studies to generate a prior led to the conclusion that protecting from piracy resulted in a significant sales boost of about 9 percent.