I am interested in the how the casinos approach this. Assume that the casino conducts a survey of potential bettors and determines that if the over-under for the Cubs is set at 89.5, then 50% of gamblers will bet the over and 50% will bet the under. Also assume that the casino asks its experts how many games they expect the Cubs to win and they say 80. In this example, it seems to me that if the casino is risk averse, it will set the over-under at 89.5, so that the casino is guaranteed to win the vig, and the casino could care less what its sports expert says. On the other hand, maybe the casino takes into account the fact that Cubs fans tend to be stupidly optimistic (for decades), and might therefore rely on its sports analysts to make some money off of the stupidity by setting the line lower so that more than 50% of the bets will be on the over. I also wonder about the impact of competition. As a gambler, I look for the best line and will bet there if it is anywhere near my hotel. I wonder if this affects how the lines are set and changed. I have bet the Twins on the over two years in a row and lost both times. As a gambler I would bet the under this year, but as a fan I will bet the over.