I was watching a sports guy talk about CFL and he was saying stuff like:
Edmonton vs Vancouver expect Edmonton by 5
Calagry vs Toronto expect Toronto by 4.5
What the hell does that mean? I always though that the point spread would be how many points the winning team would win by, but then I see numbers that don’t make sense in football (half points).
MtM
The half points are there for two reasons:
The bookmakers goal is to get an equal amount of money bet on each side. That way he is guaranteed to make money. And most bookmakers are very good at making sure they make money.
The half points are, as BobT stated, to prevent ties. If the favoured team wins by 3 points, and the spread is 3 points, did they beat the spread or not? Making the spread 3.5 eliminates all ambiguity.
As for what it means, it’s to encourage people to bet on the less-favoured team. It’s as if you and a friend were betting on the outcome of a Waukeegan Winners vs Louisville Losers game. Naturally enough, both of you feel the outcome is pretty much in Waukeegan’s favour, so you tell your friend, “I’ll bet Waukeegan not only wins, but wins by 5 or more points!” This makes betting on Louisville a more tempting proposition.
In the case of a professional bookie, he wants half the bets on Waukeegan (on which he collects a 10% fee) and the other half on Louisville (on which he also collects a 10% fee). That way, no matter which team wins, the bookie makes his 10%. If the betting heavily favours one team, the bookie will adjust the “spread” accordingly, encouraging later bettors to the other team, to bring the bets back into balance. Naturally, this involves much book-keeping, since a player who bet on Waukeegan early might have gotten a spread of 3.5, while one who bets on Waukeegan closer to game time might get a spread of 5.5. If Waukeegan wins by 4 points, the first player collects while the second does not.
Baseball lines are different than point spreads. This is an example of what a baseball line would look like: Oakland 6.5-4.5 Kansas City. From what I understand, this means that you have to bet $6.5 to win $4.5. So, Oakland is the favorite and for any dollar amount you wish to bet, you have to use the 6.5/4.5 multiplier to get the desired amount.
So how does one “beat the points”.
If a bookie has team A over Team B by 6 points. Do you beat the spread by team A winning by less or more than 6 points? What if they win by exactly 6 points?
Do the payouts varry?
MtM
A spread system will pay off 1-to-1, i.e. bet $50 and if you win, you’ll win $50. The bookie makes his money from charging you 10%, in this case $5, for the privilege of maing the bet (percentages vary by bookie).
If A is over B by 6, A has to win by at least 6 points for the A gamblers to win. Otherwise the B gamblers win. You can see how this penalizes the better team (for betting purposes), so the bookie is trying to encourage gamblers to go with B, which most wouldn’t do without that penalty to make things more fair.
If A wins by exactly 6, some novice gamblers will no doubt start nitpicking that A didn’t really “beat” the spread, so the half-points are useful in eliminating conflicts of this nature.
For a point spread the payout does not vary – for someone betting on the favored team, a win by x number of points is a win, and a win by fewer points is counted as a loss. Similarly, if you bet on the underdog, a win is a win, and so is a loss if it’s closer than the spread. Tree Boy mentions odds lines which serve a similar mathematical purpose for the bookie (ensuring that he collects as many $$ in losing bets as he pays out in winners so that he doesn’t have to cover bets with any of his commission). However, with a spread the bookie is essentially saying “Team X is favored, so I’m only going to pay out if it wins by a lot,” whereas with odds, he’s saying “Horse X is a broken-down nag, but if she manages to pull out a win I’ll pay you a ton more dough than if you bet on Horse Y, who everybody knows is probably going to win.” Odds bets make a longshot a more attractive bet by promising a big payout to accompany the greater risk; point spreads ideally make the two possible bets equal in likelihood of success.
Of course, the reason people bet is because they figure their analysis makes them smarter than the bookie – they can see that he’s set the spread too high so the favorite team will never cover or that he’s set the odds wrong so that a horse with a reasonably good chance of coming in will deliver a payout larger than the risk would justify.
–Cliffy