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How and Why We Don't Bet On It! (Part 1)

Disclaimer: Betting on sports is illegal in most states. Even if you're in a state in which sports betting is legal, you should never bet money that you cannot afford to lose. This post is purely for informational purposes. If you actually learn something from reading it, you almost certainly shouldn't be betting on sports.

The next few weekends' slates of games look pretty strong. So instead of forcing a National Game of Disinterest, I figured we could talk about the how and why (not) of sports betting.  This week we'll talk about some common types of sports bets (the how). Next week we'll talk a little bit about why betting on sports is a losing proposition.

The Point Spread: Betting on the point spread (a/k/a the line) is the most common way to gamble on sports. You've no doubt seen the notation "Some Team (-X)." For example, the line for this week's game is "Missouri at Georgia (-8)." The 8 is the point spread. The fact that Georgia is listed as "-8" means that Georgia is favored by 8 points. If you want to bet on Georgia against the point spread in this week's game, Georgia must win by at least 8 points for you to win the bet. If Georgia wins by fewer than 8 points (or if Mizzou wins outright), you lose the bet. But if you bet on Mizzou, if they won outright or lost by fewer than 8 points, you would win your bet against the spread.

Why is the favorite listed with a minus sign? When you're betting the point spread, you're really betting on the final score. In our example, if you bet on Georgia (-8), what you're really doing is saying that you could subtract 8 from Georgia's final score and they would still win the game. If you bet the other side (Missouri (+8)), you're betting that if you gave Missouri an extra 8 points at the end of the game, they would win.*  So saying, "Missouri at Georgia (-8)" is the same as saying, "Missouri (+8) at Georgia." Sports books give the point spread next to the name of the favored team (i.e., "Georgia (-8)") as a matter of convention.

* This addition and subtraction is why betting on the favorite against the spread is called laying the points and betting on the underdog is called taking the points.

Why are some spreads listed in increments of .5? Teams can't score half a point. That's precisely the point. The half-point prevents a tie (a/k/a a push) between the sports book and the bettor. In our example, if Georgia won by exactly 8 points, there would be a push, and the sports books would give the money back to everyone who bet on the game. It's like the bet never happened. That's not very fun (or profitable), so oftentimes the sports book will prevent it by giving a spread like 7.5 or 8.5 instead of 8.

The Over/Under: The over/under is the second most common type of bet, but it's also the most misunderstood. When people talk about the over/under, they're usually talking about a bet involving the final score for both teams combined. The over/under for our game this weekend is 63.5. If you bet the over, you're wagering that both teams will combine to score more than 63.5 points. If you bet the under, you're wagering that the teams will combine for fewer than 63.5 points.

Exotic Over/Unders: As MaconDawg has shown in recent Friday Tailgates, over/unders aren't confined to final scores. You can make an over/under bet on just about anything that can be quantified. That is, if you can put a number on something, you can make up an over/under. So typical over/under bets involve passing yards, passing attempts, rushing yards, turnovers, etc. It's important to distinguish an over/under from the odds of a particular event occurring. The over/under is a bet about whether some number (e.g. rushing yards) will be more or less than some set amount (e.g. 150). If you want to bet on the odds of some event occurring, you're looking for...

Prop Bets: Prop bets are the purest form of gambling. If you've ever said, "I bet I can make this shot," you were making a prop bet. Prop bets are yes/no wagers. You're betting on whether or not some event (the proposition) will occur. Popular prop bets include "Player A will win the Heisman Trophy," "Player B will catch a touchdown pass," and "Player C will score a rushing touchdown." The payout on a prop bet will be listed as +X or -X. A plus sign means that you will win that amount if you bet $100. A minus sign means that you must bet that amount to win $100. So, for example, a sports book might list a bet on Aaron Murray winning the Heisman at "+1150." That means that if you bet $100 on Aaron Murray winning the Heisman, and then he did it, you would win $1,150. On the other hand, a bet about whether Aaron Murray will throw more than one touchdown pass this weekend might be listed at "-500."  That would mean that you would need to bet $500 to win $100 if Aaron Murray threw more than one TD. One particularly important prop bet is...

The Moneyline: The moneyline is just a prop bet about which team will win outright, and the payout is listed just like any other prop bet's payout. So the moneylines for our game this weekend are Missouri (+260) and Georgia (-320). That means that if you bet $100 on Mizzou, you would win $260 if the Tigers won, but you would have to bet $320 on UGA in order to win $100 if the Bulldogs win. Georgia's basically a 3:1 favorite, but you have to list a different moneyline for each team because of...

Vigorish: The vig is the fee that the sports book is charging you to place a bet. It's reflected in the payouts. Without the vig, the moneylines for this weekend's game would be Missouri (+300) and Georgia (-300) because Vegas thinks the Dawgs are 3:1 favorites. But with the vig the sports book pays you a little less than the odds suggest you should get paid for betting on the underdog (+260 instead of +300), and the sports book requires you to pay a little more to win $100 than the odds suggest you should have to pay to bet on the favorite (-320 instead of -300).

The vig applies to every bet at the sports book, including bets against the spread. So, for example, if you went to a sports book to bet on this weekend's game, the full listing on the spread would be something like "Missouri at Georgia (-8) -110." That means that you would have to bet $110 to win $100 on your bet against the spread.

That's just about all you need to know to bet on sporting events. But, as we'll explain next week, you shouldn't actually ever do it. Until then...

Go Dawgs!