Out-of-home viewing measured in a test of Portable People Meters lifted TV ratings by 7% to 9%, according to Nielsen.
The data comes at a time when TV networks are claiming that lower ratings are the result of people watching programming via platforms and on devices that Nielsen doesn't include in current viewer metrics.
The Portable People Meter could pick up viewing not captured by current Nielsen technology.
Nielsen conducted the test of the new equipment for three months starting in April in the Chicago market. It combined Nielsen Local People Meter panel data with viewing captured by a PPM panel to measure adults 25 to 54, both English and Spanish speakers.
Lifts varied for different dayparts and different types of programming. The lift in daytime was the largest and primetime was above average. Sports showed the biggest gains of any programming genre, up 14%, Nielsen said.
Nielsen said the test provided media buyers and sellers their first opportunity to quantify how much out of home viewing could contribute to ratings.
"Understanding how consumers view television away from home is critical to our clients and measuring out-of-home expands the viewing pie, as this test demonstrated," Nielsen executive VP and managing director Matt O'Grady said in a statement. "At Nielsen our priority is to measure audiences wherever they are viewing, both inside and outside the home, over-the-air, over-the-top and on mobile devices."