They have never met, but Dorothy Swanson of Hillsdale, Mich., and Donna Deen of Plano, Tex., have joined forces to organize a movement that they hope will liberate America from the tyranny of the Nielsen television ratings. Energized by the success they had in helping keep two shows on the air, the women have formed "Viewers for Quality Television," which could become the lobbying force for the television viewer who is sick and tired of intelligent, sophisticated shows going off the air because of low ratings.

Swanson, a former teacher and mother of three teen-agers, got hooked on "Cagney & Lacy," and helped organize the letter writing campaign that was instrumental in resurrecting the series after CBS canceled it in May 1983. "I became interested in television only because 'Cagney & Lacy' spun me around and showed me what quality television really is," she says. She got in touch with friends, who got in touch with friends, and "we wrote from May to September. It was a matter of staying with it and staying on the network. The letters weren't just that we wanted it back, but all the reasons why."

Later that year, Deen organized "Viewers Campaign for 'St. Elsewhere,' " to persuade NBC to stick with that show when it was receiving critical acclaim but low ratings. The women became aware of each other after Swanson read a Detroit newspaper column about Deen's efforts. She wrote her a letter wishing her good luck, and the two began corresponding.

Last December, the two compared notes on what shows they enjoyed and realized they were the same few programs. "We thought, gosh, I wonder if other people out there feel as we do and don't know how to express themselves, as we didn't," says Swanson. While they were still putting together the idea of an organization, a San Francisco television critic wrote about them and his column appeared in a number of other papers. In a little more than two months, Swanson and Deen have received some 400 letters from like-minded souls.

"We want to band these people together and let them know what they can do. We want the networks and advertisers to listen to us as well as those 1,700 anonymous Nielsen families," says Swanson. "We don't believe they Nielsen families accurately reflect what many of us want to watch. They determine what we watch because that's the only way there is." She believes network executives and advertisers are beginning to pay more attention to the demographic makeup of a program's audience, as opposed to audience size alone, and that this is the key to keeping quality shows on the air. "Reaching 40 million kids on an allowance who watch 'The A-Team' may not be as important as reaching 20 million upscale adults who want these shows to be around a long time and not go through a panic every spring to see if a show is going to be given one more year," says Swanson.

"We're telling them to write networks and do it in a positive way to applaud these shows and why they like it," says Swanson. "Forceful, positive letters are the kind that get read. We're also encouraging them to write advertisers and applaud them for sponsoring these shows. Most of us are in the 18 to 49 age group; we're well educated and have the disposable income to buy those products."

"Most of the quality shows start out slowly and take time to build an audience," says Deen. "We want to encourage the networks to continue with these types of programs. I think a lot of people want to influence television but don't know how to do it. What we want to do is tell them how to do it."

Their second newsletter carries the names, titles and addresses of the appropriate network executives, as well as a list of advertisers for such shows as "Cagney & Lacey," "St. Elsewhere," "Cheers," "Hill Street Blues," "Miami Vice" and "Kate & Allie." Viewers interested in getting the newsletter can write to Swanson at 28 Westwood Dr., Hillsdale, Mich. 49242.

"The one element the shows have in common is the element of humanity," says Swanson. "The very real, personal lives of these characters." The two women say they have nothing against "Dallas" or "Dynasty" but, says Swanson, "they are not enough for me. I get bored."

"The American viewing public gets the television entertainment it deserves -- is satisfied with -- is complacent with," the women wrote in a mailing. 'Cagney & Lacey,' while a rare exception, proved that the democratic process, even in television, works."

And if their methods and organization catch on, frustrated TV viewers may finally have the leverage to help keep quality shows on the air.