Local TV stations are working to tune in a new methodology for counting viewers of the 6 p.m. news and morning talk shows.

The TVB, the trade organization that represents more than 800 TV stations and TV broadcast groups, is pressing Madison Avenue to start using viewer impressions as a base for striking ad deals rather than continuing to rely on TV ratings. The idea, says Steve Lanzano, the group’s president and CEO, is to find better ways to allow advertisers to buy across multiple local outlets – not only the linear programs on a local TV station, but “across our video asserts, across our web sites, our streaming services.”

The moves are just the latest in an industry working to find better ways to measure audiences as they are growing harder to track. With TV viewers migrating to streaming video on demand and mobile content, ratings have dwindled. In the case of local TV programming, some programs no longer sustain ratings measurement. Use of impressions – the actual number of people watching, rather than the percentage of possible viewers who tuned in – would give advertisers a more granular look at local station viewership.

The push also comes as more advertisers are moving into so-called “programmatic” advertising that hinges on pre-determined algorithms to find a specific set of viewers across different media. Digital media and national TV can use viewer impressions, says Lanzano, and local TV needs to do the same to remain part of the mix.

At Interpublic Group’s Universal McCann media-buying unit, executives have worked for several years to move clients to buying based on impressions, says Kathy Doyle, executive vice president of local buying for Magna, Interpublic’s large media-investment division. “You can see ratings eroding, and cord cutting and all of that,” she says. “Knowing that trend wasn’t likely to be heading in the other direction, we felt impressions were the better way to go moving forward.”

The TVB sees the move as critical to the future health of TV stations. He feels some advertisers are turning away from lower-rated national cable networks as audiences leave traditional cable and satellite services, and feels some national advertisers could find value for their money in top-rated local programs. Moving to impressions would make buying local time easier for such categories as auto insurers and quick service restaurants, he says.

If stations don’t make the move to impressions, he adds, “we will not really move the needle in terms of national buying and getting national dollars. We will be left behind.”

Many of the TVB’s members stand behind the move, which Lanzano would like to have done by 2020.

“By simplifying the way we evaluate media across platforms, we think we will enable local TV to be included more in the decision-making process” by advertisers, says Perry Sook, CEO of Nexstar Media Group, which reaches more than 38% of U.S. TV households.

“It’s an easy execution,” says Jordan Wertlieb, president of Hearst Television, which reaches about 19% of U.S. TV viewers. “It’s important to capture all audiences and the majority may be coming from traditional television, but some of the audience is coming from the streaming services.” Impressions, he says, represent “the most efficient way to quickly aggregate all of the audiences being captured.”