Overall, of the 697 regular season games involving IA opponents in 2012, the point spread differed from the actual result by an average of 12.10 points. While that may intuitively seem high considering the reverence with which the point spread is regarded, keep in mind that the smallest amount the point spread can differ from the actual result is zero, while the largest amount is theoretically infinite (if realistically about 55). Consider that it takes about six reasonably accurate spreads (say a difference of five points) to bring the huge UCLA/Arizona outlier down to the twelve point average.

From an interesting look at Vegas vs. college football by the good folks at College Football by the Numbers.