The Betfair Prof: "Question: How do you find a missing submarine? Answer: Ask the audience"
In this week's instalment the Betfair Prof, Professor Leighton Vaughan Williams, tells us a tale of old about how betting markets do more than make people money, they help the US Navy find submarines...
During a car journey between Nottingham and Warwick the other week I was told a story about the value of crowd wisdom in turning up buried treasure. The story was that by asking a host of people, each with a little knowledge of ships, sailing and the sea, where a vessel is likely to have sunk in years gone by, it is possible with astonishing accuracy to pinpoint the wreck and the bounty within. Individually, each of those contributing a guess as to the location is limited to their special knowledge, whether of winds or tides or surf or sailors, but the idea is that together their combined wisdom (arrived at by averaging their guesses) could pinpoint the treasure more accurately than a range of other predictive tools. At least that's the way it was told to me by an economist who was in turn told the story by a physicist friend.
To any advocate of the power of prediction markets, this certainly sounds plausible, so I decided to investigate further. Soon I was getting acquainted with the fascinating tale of the submarine USS Scorpion, as related by Mark Rubinstein, Professor of Applied Investment Analysis at the University of California at Berkeley. In a fascinating paper titled, 'Rational Markets? Yes or No? The Affirmative Case', he tells of a story related in a book called 'Blind Man's Bluff: The Untold Story of American Submarine Espionage' by Sherry Sontag and Christopher Drew.
The book tells how on the afternoon of May 27, 1968, the submarine USS Scorpion was declared missing with all 99 men aboard. It was known that she must be lost at some point below the surface of the Atlantic Ocean within a circle 20 miles wide. This information was of some help, of course, but not enough to determine even five months later where she could actually be found.
The Navy had all but given up hope of finding the submarine when John Craven, who was their top deep-water scientist, came up with a plan which pre-dated the explosion of interest in prediction markets by decades. He simply turned to a group of submarine and salvage experts and asked them to bet on the probabilities of what could have happened. Taking an average of their responses, he was able to identify the location of the missing vessel to within a furlong (220 yards) of its actual location. The sub was found.
Sontag and Drew also relate the story of how the Navy located a live hydrogen bomb lost by the Air Force, albeit without reference in that case to the wisdom of crowds. Perhaps, though, that tale is too secret yet to be told!
What then, I wonder, would those scientific giants, Karl Pearson and Lord Rayleigh, have made of it all? It was their correspondence, you may recall, in the pages of the scientific journal, 'Nature', which answered the classic query of where to find the drunk you left in a field. "Where you left him," was the answer. Which is all very well, of course, if you were sober enough yourself to know exactly where that might have been!
Professor Leighton Vaughan Williams is the Director of the Political Forecasting Unit and Betting Research Unit of Nottingham Business School, Nottingham Trent University, and Editor of the Journal of Prediction Markets