NBA Betting Against the Public 2004-05


This is the second in a series of articles that will examine the betting data found on Sports Insights. The goal to evaluate past results and highlight inefficiencies in the sports betting marketplace. This article only deals with the NBA 2004-05 season. We are currently working on adding 2003-04 season. This article examines betting on Home Underdogs, and Home Underdogs getting 3,5,7pts.

Home Underdog Bias:

The following information is for educational and entertainment purposed only. The staff at has spent countless hours working to ensure all data used in our analysis is correct. The data used comes from our official archived info pages. We do not guarantee our data is error free…although we’re tried our hardest to make sure every score and percentage is correct.

It is the core belief of that inefficiencies exist in the sports betting market. These inefficiencies are cause by the public’s psychological bias toward betting Favorites. Nobody likes betting on bad teams. It’s even hard for us to bet on horrible teams, but it is exactly this reason that produces a sizeable bias in the sports betting market. In the following series of article, we demonstrate that inefficiencies exist in the sports betting market and we explain strategies for exploiting it.

It is impossible to predict the future. It is possible to use statistical analysis and risk modeling to test for inefficiencies in any marketplace. There is a fallacy that exists in sports betting. Sportsbooks DO NOT look to balance their action. Oddsmakers know that the public disproportionately bet’s Favorites. They factor this bias in when they create betting odds.  It is this public bias (betting favorites) that we look to measure.

We do not guarantee that the trends and bias we’ve found will continue to exist. Any serious academic research in the field of marketplace efficiencies realizes that over time these inefficiencies will disappear.  Once an inefficiency is discovered, it is only a matter of time until the market corrects itself. The following is a summary of our findings.

NBA Home Underdog Bias  with Betting Against the Public: 10/31/04-1/25/05 ONLY 2004-05 Season

Rules for Filtering Games:

  • Did not use data if it was 0% or 100%
  • NBA Data from 10/31/04 – 1/25/05
  • Correct for 12/24/04 data error (entered twice)
  • We will include the 03-04 season in a couple of days

We evaluate the “Bet Against the Public” strategy using the following criteri:

  • % bet threshold
  • home underdog
  • home underdog getting 3,5,7pts
  • Evaluate only straight bet %

Betting Against the Public

Public Bet % # Games Win %
<35 139 54.67
<30 75 58.66
<25 38 55.26
<20 12 75.0

 When Betting on an Underdog:

Public Bet % # Games Win %
35 123 56.91
30 71 59.15
25 37 56.76
20 12 75.0

When Betting on an Underdog getting +3 or more

Public Bet % # Games Win %
<35 50 56.00
<30 39 56.41
<25 25 60
<20 8 75.0

When Betting on an Underdog getting +5 or more

Public Bet % # Games Win %
<35 33 57.58
<30 27 62.96
<25 16 68.97
<20 4 100.0

When Betting on an Underdog getting +7 or more

Public Bet % # Games Win %
<35 19 63.16
<30 17 58.82
<25 12 66.66
<20 4 100