Vampyr, on 2012-February-06, 17:46, said:
But what you are saying makes sense if people tend to "bet with their hearts" and not with their heads.
I suspect as well it has to do with the size of the fan bases. In the UK, a lot of sports betting is done by independents, ie, those who dont really support either team, but just like to watch foot ball and so put a bet on a match every week. If this is the case, simply making the odds close to the RL chances will ensure roughly the same number bet each way.
If the betting on a match is dominated by the fan bases, this will not work if the fan bases are different sizes. Moreover, attempting to change the odds to make it work leaves arbitrage opportunities for professional gamblers. The odds cannot move away from the RL chances. However, a spread bet can change this. Particularly if your betting fans are not that clear. Suppose your model/prediction is for A to beat B by ten points. If you give a handicap of 5 points on the spread, does that make B twice as likely to win? three times as likely? answer - it depends on the variance. If humans are bad at estimating the effects of the handicap on the outcome, then that increases the action for the book maker, independently of the other effects. If team B's fan base is smaller, it will also lower the bookies risk of losing a lot of money on the bet, since more of the bets will cancel out if the unexpected happens.