The original Tour Tempo's subtitle proclaimed: Golf's Last Secret Finally Revealed. At the time, it was a pretty bold claim. Today, however, Tour Tempo's premises have been backed up and validated by an independent scientific study performed by the Departments of Physics and Biomechanics at Yale University. To test the provocative thesis of Tour Tempo, Yale professors Robert Grober and Jacek Cholewicki had enlisted the cooperation (and students) of three prominent golf instructors: Bill Greenleaf, PGA Master Professional; Michael Hebron, PGA Master Professional and former National PGA Teacher of the Year; and David Leadbetter, founder and chief instructor of the worldwide David Leadbetter Golf Academy network. The students ranged in golfing ability from "tour professionals" and "teaching professionals" to "average weekend golfers, " and their swings were timed with "motion sensing accelerometers and wireless communications electronics mounted in the shaft" with sampling rates "of order 250 Hz, yielding eight times more detail than that obtained from conventional video. " Armed with this new data from the study, the Yale professors found that the data for playing professionals was consistent with the data that was reported in Tour Tempo. Additionally, Tour Pros exhibited very small values of standard deviation relative to all other golfers, meaning that their swings are very reproducible. They also concluded that the standard deviations measured for the other groups - "teaching professionals" to "average weekend golfers" - were "much larger" than that of tour professionals. "Additionally, " continued the authors, "the golf swings of professional golfers are universally faster than that of the average golfer. " The Titleist Performance Institute's 3D research data, culled from the analysis of tour-pro swings, also confirms the results of the Yale University study. TPI's researchers concluded that "Tour Tempo is the only golf training aid that has been validated by an independent scientific study. " Published in 2004 by Doubleday and written by John Novosel and Sports Illustrated senior writer John Garrity, Tour Tempo challenged the myths surrounding golf's most elusive fundamental and explained how amateur golfers could dramatically improve their ball striking--instantly, in most cases--by copying the swing rhythm of the pros. Its main premise--that tempo, the most important fundamental of the golf swing, can be learned quickly and easily without expensive lessons or exhaustive practice--is now accepted by swing coaches at every level of the game. And, now PGA tour pros including Major Championship Winners work Tour Tempo training into their practice routines.