A number of studies show that piracy helps movies, TV shows, and music albums find a much wider audience, which in turn, often times, help in boosting their revenue. But what about comic books? A new academic study shows that piracy can have a positive effect on comic book sales, too, albeit under certain conditions. From a report on TorrentFreak: Manga, in particular, has traditionally been very popular on file-sharing networks and sites. These are dozens of large sites dedicated to the comics, which are downloaded in their millions. According to the anti-piracy group CODA, which represents Japanese comic publishers, piracy losses overseas are estimated to be double the size of overseas legal revenue. With this in mind, Professor Tatsuo Tanaka of the Faculty of Economics at Keio University decided to look more closely at how piracy interacts with legal sales. In a natural experiment, he examined how the availability of pirated comic books affected revenue. Interestingly, the results show that decreased availability of pirated comics doesn't always help sales. In fact, for comics that no longer release new volumes, the effect is reversed. "Piracy decreases sales of ongoing comics, but it increases sales of completed comics," Professor Tanaka writes. "To put this another way, displacement effect is dominant for ongoing comics, and advertisement effect is dominant for completed comics," he adds.