The data from Marketing Evaluations Inc., creators of the so-called Q ratings, has long been used by TV networks to program their schedules, based on the popularity and familiarity shows and actors have with TV viewers. But another aspect of the Q data, known as "Impact Q Scores," is being used by agencies as a proxy for engagement.

"It's primarily used by media buyers to help select the most effective programs for their advertiser clients," says Henry Schafer, executive vice president of Marketing Evaluations.

Many researchers have begun to produce so-called audience engagement data, including IAG Research. Nielsen also has created an experimental "engagement panel," comprised of former TV meter households who agree to keep their meters connected and supplement that research with additional surveys on engagement after they leave Nielsen's official ratings sample. Marketing Evaluations advantage is that it has been around for decades and has been the basis of network programming decisions for much of that time.

According to Schafer, the Impact Q enable advertisers and media buyers to glean the best advertising environments based on the frequency of viewing among "favorite" program viewers.

Using those criteria, ABC's top-rated "Desperate Housewives" falls out of the top 10 in Marketing Evaluations impact scores, dropping to No. 11.

Other surprising shifts that occur when comparing Marketing Evaluations' data to Nielsen's include NBC's "ER," which ranks near the top of Nielsen's ratings, but is only 16th in Marketing Evaluations' database.

Interestingly, ABC which seems to dominate Nielsen's universe, appears to be an also-ran in Marketing Evaluations', placing only one show - "Grey's Anatomy," ranked No. 2 - in the top 10, and only four shows in the top 20 Impact Q scores.

CBS, with five of the top 10, and seven of the top 20; and Fox with five of the top 20, fare the best.