Interesting article
http://www.philsteele.com/blogs/2012/Aug12/DBAug1.html
"There have been 576 games in which a team was favored by 3 points by Las Vegas over the last 15 years. How many times does that team win outright? The answer is 319 times or 55.4% of the time. That is 319 times the favorite has won and 257 times the underdog has won which means the underdog is almost as likely as the favorite to win the game when the line is exactly 3 points. "
http://www.philsteele.com/blogs/2012/Aug12/DBAug1.html
"There have been 576 games in which a team was favored by 3 points by Las Vegas over the last 15 years. How many times does that team win outright? The answer is 319 times or 55.4% of the time. That is 319 times the favorite has won and 257 times the underdog has won which means the underdog is almost as likely as the favorite to win the game when the line is exactly 3 points. "