A partnership between a top magazine publisher and a major ad buyer is advancing magazines' long push to get measured just like most other media: by their audiences, not just paid circulations.

Time Inc. and Starcom MediaVest Group began the partnership last year to find a way to promise advertisers that certain numbers of people would recall their ad campaigns or take action on them. That effort, which they called the Alliance for Magazine Accountability, has now progressed beyond the development phase and is available to any interested Starcom MediaVest client making a big enough buy with Time Inc.

Guaranteeing effectiveness is notable, and more than most media players will do, but the program is also significant because it emphasizes audience over paid circulation.

"Moving forward, all of our clients have the option to participate and replace their traditional circulation guarantee with an ad-audience and ad-performance guarantee," said John Muszynski, chief investment officer at SMGX, a Starcom MediaVest unit where the group's agencies share resources and try new models.

"It was getting everybody to believe that magazines can give an audience guarantee," said Stephanie George, exec VP and chief marketing officer at Time Inc. "We're not this fractured medium that has to be evaluated by just our circulation."

Paid circulation remains an important measure, Ms. George said, and one that 's available to any Time Inc. client that wants it. But using the same metric as other media -- audience -- makes it easier for advertisers to stack magazines' reach up against everyone else and consider them for pieces of big multimedia campaigns.

Audience figures also make the scope of magazines' reach more obvious because they account for copies shared among family or in waiting rooms. Time magazine attracted an audience of nearly 19 million people in the most recent research from GfK MRI, for example, compared to its average paid circulation of 3.3 million.

Publishers and magazine executives have been bemoaning the emphasis on paid circulation for years, but change has been slow to come. "Paid circulation rate-base guarantees are a legacy of an era that predates modern audience measurement metrics," Magazine Publishers of America Chairman Jack Kliger told the American Magazine Conference in 2005. "Circulation-based metrics are irrelevant in calculating advertising return on investment."