But researchers find that since BitTorrent emerged, international box office returns for U.S. films have been 7 percent lower than they likely would have been absent the torrents.

A study looking at the correlation between the appearance of BitTorrent in 2003 and loss of box office revenue by Hollywood films due to piracy suggests that U.S. box revenue has largely been unaffected but that international returns have been lower than they might otherwise have been absent pre-release piracy.

An abstract for the study by Brett Danaher of Wellesley College and Joel Waldfogel of the University of Minnesota is dated Jan. 16, but it just started making the rounds in the tech press on Friday.

The researchers looked at the period following the appearance of BitTorrent, but didn't indicate that they were focused just on that particular torrent. Rather they looked at what might be called the "torrent era" as a whole, measuring actual box office returns for Hollywood movies both domestically and internationally during the period against pre-torrent rates of return.

What Danaher and Waldfogel found might not be welcome news for anti-piracy advocates. For starters, the researchers say they "do not see evidence of elevated sales displacement in US box office revenue following the adoption of BitTorrent."

However, box office revenue for U.S. films has been diminished in international markets during the torrent era. But the researchers suggest that the effect is even more strongly correlated to lag times between a film's U.S. release and its release in a particular country than to the rise of online piracy.

With the growth in movie piracy since the appearance of BitTorrent in 2003, films have become available through illegal piracy immediately after release in the U.S., while they are not available for legal viewing abroad until their foreign premieres in each country," the researchers write. "We make use of this variation in international release lags to ask whether longer lagswhich facilitate more local pre-release piracydepress theatrical box office receipts, particularly after the widespread adoption of BitTorrent. We find that longer release windows are associated with decreased box office returns, even after controlling for film and country fixed effects."

The study also found that the relationship between decreased box office returns and long release windows was "much stronger in contexts where piracy is more prevalent: after BitTorrent's adoption and in heavily pirated genres."

The final verdict: international box office returns for Hollywood films "were at least 7 percent lower than they would have been in the absence of pre-release piracy," which the researchers contend is the direct result of delayed legal availability of U.S. titles in foreign markets.