WASHINGTON – Domestic violence against women rose in regions whose NFL teams lost important games they were expected to win, US research findings showed Tuesday.

Researchers funded by the US National Institutes of Health reported a 10 percent rise in domestic violence reports to police in areas where teams lost unexpectedly, according to their analysis of 900 regular season games.

The increase jumped to 20 percent when the region's team lost a game they were favored to win against a traditional rival.

"Our results suggest that the overall rise in violence between intimate partners we studied is driven entirely by losses in games that matter most to fans," said co-author David Card, an economics professor at the University of California at Berkeley.

Card and Gordon Dahl, an economics professor at the University of California in San Diego, collected and studied data, including pre-game betting odds, on regular-season games of six National Football League teams between 1995 and 2006.

The information was matched to records collected from 763 local police jurisdictions. The violence typically occurred toward the end of the games and in the two hours following the end of games.

The pattern of violence was most pronounced for the most important games, the researchers said.

"Violence was also more likely to increase when the local team was still in playoff contention or had a particularly frustrating performance," such as four or more sacks of quarterbacks or turnovers, they said in a statement.

Card and Dahl found no decrease in reports of domestic violence following an unexpected victory by the local team, or by the team's loss in a game that was expected to be close.

They said the findings confirm their earlier analysis suggesting unexpected disappointments affect people more strongly than pleasant surprises.

"This is not limited to football," Card said. "Someone who gets a speeding ticket on the way home, for example, might also be more likely to act out in a way he would later regret."

The findings were published in the Quarterly Journal of Economics.