Because the spread is intended to create an equal number of wagers on either side, the implied probability is 50% for both sides of the wager. To profit, the bookmaker must pay one side (or both sides) less than this notional amount. In practice, spreads may be perceived as slightly favoring one side, and bookmakers often revise their odds to manage their event risk.
For example, in a cricket match a sports spread betting firm may list the spread of a team’s predicted runs at 340 – 350. The gambler can elect to ‘buy’ at 350 if they think the team will score more than 350 runs in total, or sell at 340 if they think the team will score less than 340. If the gambler elects to buy at 350 and the team scores 400 runs in total, the gambler will have won 50 unit points multiplied by their initial stake. But if the team only scores 300 runs then the gambler will have lost 50 unit points multiplied by their initial stake.
In this example, we have a favorite to win, and an underdog. The Packers are the favorites, and that is shown by the (–) value in front of the 6. Underdogs are represented by the (+) value. The 6 point value is how many points either team could win, or lose by. If you think the Packers will win by MORE than 6 points, then you’d bet on the favorite in this case, meaning that the Packers have to win by 7 or more points in order for you to win your bet.