How can someone guess the betting lines for a sporting event?

April 6, 2010 7:13 AM

How does one guess sports betting odds, or determine at what point to place a bet on a sporting event?

I'm a huge fan of Bill Simmons on ESPN. Every NFL season, he and a friend named Cousin Sal will do a weekly podcast where they guess the lines on NFL games. I'm mystified as to how they make educated guesses on what the lines will be.

What sorts of factors would go into consideration in guessing the odds for sporting events, and is there a model that can predict when a person should or should not bet on a sporting event?

BONUS QUESTION: Can someone explain in a simple fashion how to bet using a money line?

Thanks!

posted by reenum to grab bag (9 answers total)

about.com does a fine job with moneylines
posted by rakish_yet_centered at 7:39 AM on April 6, 2010

Experience watching lots of games, betting on lots of games, and having an idea of "public perception."

Home-field advantage is generally considered to be worth 3 points in the NFL.
3, 4, 7 and 10 are considered "big" numbers in NFL spreads (3 and 7 especially). They are the most common outcomes and so tend to be the most common lines. Moving "off" of 3 or 7 (from 3 to 3.5 or 2.5 to 3) is a much bigger move than from, say, 5 to 5.5 or 1.5 to 2.

As for determining what to bet, or a model for betting, if I had one, I ain't sharing it. Lots of money is made by people who bet correctly on sporting events, even though 90% of people who bet are long-term losers.

This is sort of like asking "is there a model that can tell me when to invest in the stock market?" Lots of people will say yes but few will be right.
posted by jckll at 7:40 AM on April 6, 2010

I'd say any time someone is offering odds different from Vegas's, it's probably a good bet. Vegas has a LOT of money riding on their lines being good.

As for how Vegas does it, I believe they take into account not just the game, but all of the other line-setters' lines, so it's sort of a wisdom of the crowd kind of thing.
posted by callmejay at 8:39 AM on April 6, 2010

(Oh, and they obviously take into account all the bets being made as well, so the crowd is even bigger.)
posted by callmejay at 8:41 AM on April 6, 2010

I read this Wired article a few years back about computer-assisted handicapping of horseraces in Hong Kong, I think it came from the Blue in fact (found it in AskMe). It might be of interest, it covers model creation.
posted by rakish_yet_centered at 9:27 AM on April 6, 2010

Wrt point spreads, the idea is to get the same amount of money bet on either side of the spread, thus locking in the house cut as profit.

Simplified:
In vegas you generally bet 110 to win 100. With a 110 bet on either side of the spread the the casino gets 220 in but gives back only 210 to the winner (the original wager plus the 100 winnings). the 10 profit is locked in as long as there is a bet on both sides of the spread.

Multiply that by tens of thousands of bets. Therefore, the goal is not so much to assess the likely outcome of the game as the likely sentiment of the bettors.
posted by dzot at 10:03 AM on April 6, 2010

Wrt point spreads, the idea is to get the same amount of money bet on either side of the spread, thus locking in the house cut as profit.

Yes and no. This is true in theory and it is how most people learn about the way lines are "made," but in practice it isn't really true. On nearly every game, nearly every sportsbook is taking a side one way or the other. They tend to be right more often than the average bettor.
posted by jckll at 10:31 AM on April 6, 2010

The money line wager is simple. You pick a team to win. Most of the time there will be a favorite and an underdog. The payout will pay more per dollar wagered on the underdog than on the favorite.

Example:

New York Yankees: -120
Toronto Blue Jays: +115

This means that for every $120 you bet on the Yankees, you stand to win $100, and for every $100 you bet on the Blue Jays, you stand to win $115.
posted by clearly at 5:54 PM on April 6, 2010

In sports betting against the line, as dzot said above, you generally win $100 for every $110 you bet. This is the norm and you may see some slight variation.

When setting a line, sportsbooks are not trying to predict the outcome of the game. They are trying to pick a point where each side has approximately 50% of the total money wagered. A perfect line for the sportsbook is one where exactly 50% of the money is on each side. Since the payouts are -110, the sportsbook pays the winners with the loser's money and still takes approximately a 10% cut of the total money wagered on that line.

Line movement is an attempt to correct for a heavy amount of money wagered on one side of the line. If a majority of the money is bet on one side, the line will move to favor the other side, as an attempt to make it more appealing to bettors, and to even out the wagers on each side.
posted by clearly at 6:06 PM on April 6, 2010