Explain the odds?

I used to pester my father to explain the type of odds printed in newspapers. Since he’s no longer available to pester, I’m pestering you.

What do odds like these mean?

I’m assuming that the Cardinals are favored to win. But what are these numbers?

That chart is kind of a mess.

For starters, the 8.5 is the Over/Under. You can bet on whether the total scored will be greater than 8.5 or less than 8.5.

Usually, when you’re actually betting, you’ll see something like this:

St. Louis -200
San Diego +180

What that means is that you need to bet 200 to win 100 (or 200 returns 300) on St. Louis. You need to bet 100 to win 180 (100 returns 280) on SD.

If bookies didn’t want to make money, it would be listed as +/- 190. So, for STL, you could bet 190 to win 100, and for SD you could bet 100 to win 190. That represents what they think are the true odds, but they don’t pay you the true odds. And usually, to save space, that’s how a newspaper will list it. If you see 190 in the paper and you call your bookie, he’ll only give you +180/-200 or something like that.

Sometimes, they list what the line opens at. So, that might have opened at +200/-220, for instance, but the action pushed it to +180/-200.

But, your link kind of has it all convoluted.

The numbers reflect the betting odds as gathered from various casinos; the expert odds include what the values were when first posted, then as they are now.

The “-260” next to St. Louis ("-250" at the Stardust and Mirage) indicate the number of dollars you would have to bet on St. Louis to win your bet plus $100; if St. Louis wins, you take home $360. The reverse would be true if you bet on San Diego to win–$100 bet gives you a chance to win $360–but there is an additional $10 vig–a betting fee–added, so you really have to bet $110 to win $360 (I may have the vig reversed; someone who gambles more often than I should know).

The other number in the column, in this case “8.5”, is the line for the total number of runs expected in the game.

As for why there is a +/- next to the dollar bet for a team, I’m not sure it’s relevant, but given the complexities of sports gambling I’m sure it is…

The +/- helps to identify which team is favored. Minus is the favorite, and plus is the underdog.

Bets on baseball and hockey are usually proposition bets, meaning you bet a fixed amount and are paid off a certain mount if that team wins. In basketball and football, betting is typically based on a point spread (although in fact most sports books also offer proposition betting on tehse sports).

… so I’ve heard.

For instance, at Yahoo, the same games are listed like this. . .



Favorite       Line   Underdog   Line 
at St. Louis  -250    San Diego   220 
at Atlanta    -130    Houston     120 


That makes sense for what I posted earlier.

The reason that there’s a “30 cent” difference for the STL game and a “10 cent” difference for the ATL game is a little complicated.

If you care, the easiest way to explain it is by an example.

Let’s say teams are evenly matched, and your bookie gives you a “10 cent line”
-105
-105

(you need to bet 105 to win 100).

If you play that 10 times, betting $105 each time. 5 times you’re expected to win $100 and 5 times you’re expected to lose $105, so you’re out $25. That’s the same no matter which team you pick.

Now, let’s say a team was a 9-1 favorite. If they did “10 cent lines”, the odds would be

+895
-905

If you bet the favorite in that (at $905), 9 times you can expect to win 100. 1 times you lose $905.

If you bet the underdog in that on average: 9 times you would lose $100, and one time you would win $895.

That means that out of 10 bets, the bookie has only won $5.

So, when the odds get more skewed, the books build more juice into them. Sometimes for a fight, you’ll see odds like +500/-700.

As a friend of mine told me, who is involved in some of this sort of betting, the idea behind the lines is to equalize the betting. (Bookies anyway).

They aren’t trying to make money off the win/loss of the actual bets, but rather trying to make sure that the amount of risk involved in one side winning is offset by the losses by the other side’s bets.

The bookie makes money off the “vig,” which is the percentage you pay to such a person for the privlege of making the bet…

Or that’s how I understand it anyway.

-Butler

I believe you are correct. Bookies aren’t in the business of deciding the true odds of a team winning or losing. Their odds are made by cruching numbers on bets already placed, noticing trends, and adjusting their odds to get equal dollar values bets on both sides. They are always guaranteed to win if they do it correctly.