Out-of -home viewership lifted this year's Super Bowl audience by at least 20.7%, depending on the demographic, according to data collected by media-and-marketing-research firm Arbitron.

Using data based on a panel of 70,000 people, Arbitron determined that audiences in two key advertiser-desired demographics increased significantly when viewers watching Super Bowl XLVI away from their own TV sets were taken into consideration.

For adults 18 to 49, out-of -home viewing delivered an audience lift of 25.4% over in-home-only viewing levels, according to Arbitron, which defines "lift" as the number of away-from-home viewers divided by the number of in-home viewers.

Among adults over 18, Arbitron found that 11.9 million people watched the New York Giants defeat the New England Patriots from an "out-of -home" venue, usually someone else's house. "Viewing in other people's homes is always the biggest contributor to out-of -home," said Carol Edwards, senior VP-sales and marketing for Arbitron's cross-platform media.

The initial Nielsen ratings released last week account only for people who watched the Super Bowl live in their own homes.

While traditional Nielsen TV ratings remain the predominant measure of ascertaining the performance of the Super Bowl, one media buyer suggested that outsize events such as this annual TV staple are ripe for additional statistics. "Sports are social events," said Sam Sotiriou, senior VP-media research for Publicis Groupe 's Zenith Media. "People like to get together and have a few beers. This is a unifiying event and gives people something in common to talk about."

Arbitron found that out-of -home viewing provided a lift of 20.7% to the total audience of people 18 or older, a 31.2% lift to viewers between 18 and 34, and a 23% lift to viewers between 25 and 54.

Here's Arbitron's full breakdown of the national numbers: