The Harvard Economic Service pioneered in the business of economic forecasting by publishing a quarterly journal on economic statistics and, starting in 1922, a weekly letter on economic conditions. The Harvard forecasting model, developed by the statistician and economist Warren Persons, gained international renown for its three-curve A-B-C chart, which rendered business fluctuations as the ebb and flow of speculation (A), business (B), and banking (C). The service was directed by C. J. Bullock, who promoted Harvard's forecasting service around the world by forming collaborative agreements with John Maynard Keynes, Lucien March, Corrado Gini, and other prominent economists of the time. Through these contacts, the Harvard method influenced the evolution of forecasting techniques in several European countries. The Harvard Economic Service, however, attracted criticism for its purely empirical approach, its failure to make consistently accurate predictions, and its pursuit of commercial objectives in a university setting. Harvard's efforts to build a forecasting service are an early chapter in the evolution of the social sciences, the growth of the financial analysts, and the commercialization of academic knowledge.