What is a consumer's two cents worth to a marketer? About 50 cents.

BzzAgent, a Boston-based word-of-mouth marketing agency, has fixed that amount to a conversation by one of its 425,000 agents on behalf of a brand.  "A 50¢ cost per conversation is the norm," said Dave Balter, president at BzzAgent.

That figure also emerged from a white paper recently released by ChatThreads, a Boston researcher, though the latter said the figure was far from definitive.

What's the norm at BzzAgent is so far staying at BzzAgent, however. The word-of-mouth marketing industy is lurching towards some sort of standardized ROI metric, but none has emerged yet. Those in the industry say the lack of such a figure isn't hurting business per se, but nevertheless, finding one has moved to the top of the agenda for the burgeoning discipline. The W-O-M marketing industry's trade group, the Word of Mouth Marketing Assn. in Chicago, has yet to settle on one.

"I don't know if we'll come up with a single standard or there's two or three different ways," said Ed Keller, Womma's president and CEO at the Keller Fay Group, a New Brunswick, N.J. word-of-mouth marketing research firm. "By the end of the year, marketers will have a better way about it."

The difficulty of pegging a metric, a la the network TV industry's CPM (cost per thousand), and a methodology to word-of-mouth calls into question the true value of viral media, an issue bedeviling digital media as well.

"It's a very hot topic," said David Bank, an analyst with RBC Capital Markets. "I might think I'm paying X amount for a CPM, but if virality is 30 times that, I'm paying so much less. If you have a 27 times virality rate, you really paid a 27th of that."

If anything, word-of-mouth marketing—which is based on a viral model—is even tougher to quantify. For its part, BzzAgent measures the success of a W-O-M campaign by dividing sales by total conversations, which is how the company arrived at the 50¢ figure.



But measuring sales can be tricky, especially if a W-O-M campaign isn't national. That's why some W-O-M practitioners, like Procter & Gamble's Tremor unit, measure success of a W-O-M effort by comparing areas where a campaign has run with places it hasn't. But sales can also be affected by other factors, like an ad campaign. Nevertheless, some think W-O-M is measurable.

Walter Carl, an assistant professor at Northeastern University and chief researcher of ChatThreads, was one of the authors of a white paper that took a crack at measuring W-O-M. Carl's formula takes into account reach, purchase behavior and other factors including marketing program costs.

In the paper, Carl outlines a six-week campaign for an unnamed "lower-involvement CPG product"  in which 1,867 participants talked to an average of 16.4 conversational partners. Eighty-three percent of those partners ("generation 2" in Carl's parlance) then spoke with an average of 1.94 others. Thus, Carl calculated the reach as 747,537. Of that number, Carl projected that 146,545 units were purchased as a result of the program.

After running the numbers, Carl's figure then came out to be 51¢, almost exactly the same as BzzAgent's. But Carl was quick to dismiss a 50¢ standard. "It varies," he said. "Almost all the inputs are variable. We've seen different values per conversation, but we haven't done enough campaigns to say what the average is."

Another way to tackle the issue is by looking at changes in a Net Promoter score. Net Promoter, a system created by Satmetrix, Foster City, Calif., gauges a W-O-M program's success by looking at how many consumers would recommend the brand or product to a friend. Deborah Eastman, CMO at Satmetrix, said the system is more a measurement of "pure word-of-mouth" than the effects of a campaign.

While she said she had no issues with the word-of-mouth industry, Eastman said she believes there are other ways to create a good buzz. "Word-of-mouth is something that's earned," Eastman said. "We believe that paying people to deliver word-of-mouth is not the right model."