A significant amount of TV viewing is missed by standard ratings methodologies because it is done out of the home, according to new research in the US.

The Total TV Audience Monitor, a survey set up by Montesano Marketing Research, claims the average quarter-hour audience in America would rise by 4% (1.7 million adults) if out-of-home viewing is accounted for. The increase is 11% among 18 to 34-year-olds, many of whom are at college.

According to the study, around 82m US adults a week visit locations outside their home with television sets. This viewing could be useful to advertisers, since the report estimates that 72% of out-of-home viewing takes place in situations "comparable to a home environment and conducive to advertising".

The most common out-of-home venue is college, with 29.5% of viewing taking place in off-campus housing and 18.6% in rooms on campus. Other locations include the workplace (13.9%), hotels and motels (13.2%), second homes (10.8%) and restaurants and bars (6.9%).

The study was based on 4,021 adults filling in personal diaries between October and November last year. It claims to be the first research to measure the total television audience since 1997.

Data sourced from: Daily Research News Online; additional content by WARC staff