Hollywood laid much of the blame for illegal movie downloading on college students. Now, it says its math was wrong.

In a 2005 study it commissioned, the Motion Picture Association of America claimed that 44 percent of the industry's domestic losses came from illegal downloading of movies by college students, who often have access to high-bandwidth networks on campus.

The MPAA has used its study to pressure colleges into tougher measures against illegal file-sharing and to back legislation currently before the House of Representatives that would force them to do so.

But now the MPAA, which represents the U.S. motion picture industry, has told education groups a "human error" in that survey caused it to get the number wrong. It now blames college students for about 15 percent of revenue loss.

The MPAA says that's still significant, and justifies a major effort by colleges and universities to crack down on illegal file-sharing.

But Mark Luker, vice president of campus IT group Educause, says it doesn't take into account that more than 80 percent of college students live off campus and aren't necessarily using college networks. He says 3 percent is a more reasonable estimate for the percentage of revenue that might be at stake on campus networks.

"The 44 percent figure was used to show that if college campuses could somehow solve this problem on this campus, then it would make a tremendous difference in the business of the motion picture industry," Luker said. The new figures prove that "any solution on campus will have only a small impact on the industry itself."

The original report, by research firm LEK, claims the U.S. motion picture industry lost $6.1 billion to piracy worldwide, with most of the losses overseas. It identified the typical movie pirate as a male age 16-24. MPAA said in a statement that no errors had been found in the study besides the percentage of revenue losses attributed to college students, but that it will hire a third party to validate the numbers.

"We take this error very seriously and have taken strong and immediate action to both investigate the root cause of this problem as well as substantiate the accuracy of the latest report," it said.