## Appendix A.1. Wagering Against the Line

When you place a wager on a football or basketball game you have to consider the line (also called the point spread or spread). For example, let's look at a college football game between Notre Dame and Navy. If both teams have an equally good chance to win, you could take a piece of paper, write Notre Dame on one side and Navy on the other, and draw a line right down the middle. The paper might look like this:

Since the line is exactly in the middle of the paper, it means that the two teams are considered to be even and that each team has an equally good chance to win. This is called a pick-em. Of course, college football fans know that Notre Dame and Navy play each other nearly every season, and Notre Dame almost always wins (although Navy ended a 43 game losing streak against Notre Dame with a triple overtime win in 2008!). Due to the past history of the series, it seems highly probable that Notre Dame will win again this time. Therefore, if the game was a pick-em, everyone would take Notre Dame. The oddsmakers don't want that to happen. They want some people to take Navy even if they think Navy will lose, and so they compensate by moving the line towards Notre Dame and away from Navy:

In the above example, the line was moved 28 points to the left of center. This means that if you wager on Notre Dame, they need to win by more than 28 points in order for you to collect your money. The notation for this wager is Notre Dame (-28). Even if Notre Dame wins by 31-7, you lose. Why? Because when you take 28 points away from Notre Dame, the score becomes 7-3 in favor of Navy. The notation for a wager on Navy is Navy (+28). They need to win or lose by 27 points or less in order for you to win your wager. If the outcome of the game falls right on the line (Notre Dame wins by 28), the game is a push and the wager is off. Often, the line is set on a half-point (27.5, for example) to eliminate the possibility of a push.

The type of wager we have just described is the most common type of sports wager. Some gamblers refer to this type of wagering as playing sides, since you simply choose a side (either Notre Dame or Navy in our example). The 28 points in our example is called the line, point spread, or simply the spread. A pick-em has a point spread of 0. Notre Dame is the favorite, and Navy is the underdog, or dog. If you play the favorite you lay points, if you play the dog, you take points. If Notre Dame wins by more than 28, or if Navy loses by less than 28, you can say that they covered the point spread.