NEW YORK (AdAge.com) -- When European adman and author Jonathan Cahill was researching his new book, "Igniting the Brand," he sifted through 27 years of Advertising Effectivess Award files. Studying the most successful campaigns from the UK, Canada, Australia, New Zealand the U.S. he was searching for patterns of what worked. But the only pattern that really stood out was the inherent unpredictability of advertising strategies themselves. His findings make him more wary of the industry's growing excitement about the new "science" of ad planning made possible by digital data.