Ad industry heavyweights at the IAB Annual Leadership Meeting in Phoenix this week wrestled with the meaning of Big Data on advertising.

The industry’s fascination with Big Data was certainly fully on display. “Big Data is the new black,” joked IAB CEO Randall Rothenberg. But Rothenberg cautioned against the misapplication of Big Data, which could result in “a deathless efficiency spiral.”

Fidelity Investments CMO Jim Speros, in a great keynote, noted that Big Data is “the electronic microscope of the 21st Century,” and is “a friend of the marketing process. Marketing is ultimately about driving growth,” said Speros. “Big Data can accomplish this with more precise targeting, and more relevant messaging based on true preferences, behaviors, patterns and insight.”

But like Rothenberg, Speros cautioned that the ad industry would be foolish to rely only on Big Data, which is too rational. Brand building is a different job, and is driven more by human intuition. Brands are “trustmarks, promise, relationships, loyalty, advocacy and desire.”

Big Data can help develop and prioritize a products features and benefits, Speros added. “But these can be copied by any company. Real insights are based on a unique understanding of the human condition.”

Longtime media strategist Michael Wolf, Managing Director at Activate, suggested that advertisers need to combine the best of “little data” and Big Data. “First, improve the user experience. Then measure advertising effectiveness,” he said. “Use data to create new user experiences, determine valuable data; and then determine user experiences that capture more data.”