In 1979, Dr. William Quirin wrote Winning at the Races: Computer Discoveries in Thoroughbred Handicapping. This seminal book brought the term “impact values” into the American racing vocabulary. Although Dr. Fred Davis’ 32-page paper, Percentages and Probabilities (1973) arrived on the scene years before, the very scope of Bill Quirin’s work was at least a full magnitude above.
Winning at the Races, along with Tom Brohamer’s Modern Pace Handicapping, and Andy Beyer’s Picking Winners, are the three single books that had the greatest impact on North American racing before the new millennium era of giant databases.
Quirin’s work impacted me in several ways. First, his version of Davis’ IVs gave me a way to study the impact of individual factors on a level that I had never had before.
Ironically, both Quirin’s and Davis’ approach to impact values had a built-in flaw.
Impact Value Formula (Davis & Quirin)
IV = Percentage Of Winners / Percentage Of Starters
When I wrote my own book, Percentages & Probabilities 2012, I corrected the formula and showed the proof of why the Q/D approach was wrong.
Impact Value Formula (Schwartz)
IV = Wins / Expected Wins
Expected Wins = Sum of 1/field in all races
One of the most powerful chapters in the book was on “Form.” This short video on Quirin Form Factors will gave you several angles that you can use to improve your game.
Without a doubt, of all the historical handicappers it is Dr. Quirin who had the greatest impact upon me. More than anything, it was his IV metric that showed me that things could be measured and concrete conclusions reached.