I hadn’t planned to make three posts, one per day, about Watson on Jeopardy!, but there ya go. The third day — the second game of the two-game tournament — was perhaps even more interesting than the first two.
Watson seemed to have a lot more trouble with the questions this time, sometimes making runs of correct answers, but at other times having confidence levels well below the buzz-in threshold. Also, at many of those times its first answer was not the correct one, and sometimes its second and even its third were not either. Some of the problems seemed to be in the categories, but some just seemed to deal with particular clues, regardless of category.
Watson also did not have domination of the buzzer this time, even when it had enough confidence to buzz in. I don’t know whether they changed anything — I suspect not, since they didn’t say so. It’s likely that Mr Jennings and Mr Rutter simply were more practiced at anticipating and timing their button-presses by then (remember that the three days’ worth of shows were all recorded at the same time, a month ago).
Those factors combined to make Watson not the run-away winner going into the Final Jeopardy! round that it was in the first game. In yesterday's final round (category: 19th-century novelists), all three contestants (and your reporter, at home) came up with the right answer, and Watson pulled far ahead with an aggressive bet that Mr Rutter didn’t have the funds to match. Mr Jennings, meanwhile, chose to be conservative: assuming he would lose to Watson (the first game’s results made that certain), he made his bet of only $1000 to ensure that he would come in second even if he got the answer wrong.
The result, then, was Watson winning the two-game match handily, and earning $1 million for two charities. Other charities will get half of Mr Jennings’s and Mr Rutter’s winnings (whether that’s before or after taxes, I don’t know; I also don’t know whether taxes will reduce Watson’s million-dollar contribution).
One other thing: in a New Scientist article yesterday, talking about the second day and the first Final Jeopardy! round, Jim Giles makes a sloppy mistake (but see update below):
Watson’s one notable error came right at the end, when it was asked to name the city that features two airports with names relating to World War II. Jennings and Rutter bet almost all their money on Chicago, which was the correct answer. Watson went for Toronto.
Even so, the error showed another side to Watson’s intelligence: knowing that it was unsure about the answer, the machine wagered less than $1000 on its answer.
Of course, Watson’s wager had nothing to do with how sure it was about the answer: it had to place the bet before the clue was revealed. Its wager had something to do with the category, but likely was far more heavily controlled by its analysis of the game position and winning strategy. In determining its bets, it runs through all the bets it and its opponents might make, and decides on a value that optimizes its own position. And its strategy in the second game was different from that in the first
Update: The New Scientist article was updated shortly after it was published. It now says this:
Even so, the error did not hurt Watson too much. Knowing that it was far ahead of Jennings and Rutter, the machine wagered less than $1000 on its answer.