Sportsbooks aren’t predicting what the total points or the margin of victory will be when the line is being set; they guess what the public perception will be.

This is why lines move. The aim of any bookmaker is to take in money equally on both sides of a line. Traditional vigorish (or juice) is about nine percent: a $110 bet earns a payout of $210 ($110 stake plus $100 in winnings).

If 10 people bet $110 on one side of a line, the bookmaker takes in $1100. If other folks throw down the same total of $1100 on the other side of that line, the book has $2200. The house has to pay out $2100 because whichever side wins gets back the original stake of $1100 plus $1000 in winnings.

The book is $100 ahead of where they started because they survive on the vig — if the money on both sides is the same. When a lopsided amount of money comes in on one side, the line moves to encourage bets on the other side of it.

The way money is made by people wagering is to identify the biases in perception. It’s not like blackjack where you’re betting against the house; it’s more like poker where you’re betting against other people, it’s just a really big virtual table everyone’s sitting at.

So the goal of the book isn’t to get the score right; it’s to live in the juice and make money. Likewise, the objective of the sports bettor is to make money. And the goal isn’t to outsmart the house; it’s to be more prepared and knowledgeable than the other bettors.

—@PoisonPill4