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SportsInsights.com Article ARTICLE # 1 NBA - BETTING AGAINST THE PUBLIC STATS
10/31/2003 - 1/25/2005
This is the first in a series of articles that will examine
the betting data found on Sports Insights. The goal is to
evaluate past results and highlight inefficiencies in the
sports betting marketplace. The first article tests the Win
% of Sports Insights "Bet Against the Public" strategy.
NBA Bet Against the Public:
The following information is for
educational and entertainment purposed only. The staff at
SportsInsights.com 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
SportsInsights.com 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 harder 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 articles, 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 bets 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
biases 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 Betting Against the Public:
10/31/03-1/25/05
Rules for Filtering Games:
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Did not use data if it was 0% or 100%
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NBA Data from 10/31/03 – 1/25/05 (1674 games)
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Correct for 12/24/04 data error (entered twice)
We evaluate the “Bet Against the
Public” strategy using the following criteria.
The following tables look at Win % if a
person bet on a team with X % (Public Bet %). Table 1
is based solely on Straight Bet %, Table 2 is based solely
on Teaser Parlay Bet %, and Table 3 is based on the average
between the two.
Table 1 NBA – Straight Bets
|
X % or Lower
(Public Bet %) |
# Games |
Win % |
Avg Marg Win |
Avg Marg Loss |
|
|
50 |
1572 |
50.6 |
9.4 |
8.4 |
|
|
45 |
1240 |
51.9 |
9.4 |
8.6 |
|
|
40 |
903 |
50.5 |
9.4 |
8.7 |
|
|
35 |
611 |
51.1 |
9.2 |
8.2 |
|
|
30 |
369 |
53.1 |
9.6 |
8.4 |
|
|
25 |
207 |
50.7 |
8.8 |
7.9 |
|
|
23 |
152 |
55.3 |
8.9 |
8.3 |
|
|
20 |
85 |
56.5 |
9.1 |
7.0 |
|
|
15 |
29 |
69.0 |
10.5 |
5.5 |
|
|
10 |
7 |
71.4 |
7.3 |
7.8 |
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Table 2 NBA –Parlay/Teaser
|
X % or Lower
(Public Bet %) |
# Games |
Win % |
Avg Marg Win |
Avg Marg Loss |
|
|
50 |
1604 |
50.9 |
9.6 |
8.2 |
|
|
45 |
1193 |
49.6 |
9.8 |
8.3 |
|
|
40 |
830 |
49.4 |
9.9 |
8.0 |
|
|
35 |
517 |
50.5 |
10.1 |
8.4 |
|
|
30 |
312 |
52.6 |
9.7 |
8.4 |
|
|
25 |
158 |
51.9 |
10.1 |
8.2 |
|
|
23 |
111 |
54.1 |
9.9 |
8.0 |
|
|
20 |
62 |
56.5 |
11.3 |
7.1 |
|
|
15 |
12 |
33.3 |
10.8 |
8.0 |
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Table 3 NBA – AVG Bets Straight &
Parlay/Teaser
|
X % or Lower
(Public Bet %) |
# Games |
Win % |
Avg Marg Win |
Avg Marg Loss |
|
|
50 |
1617 |
50.9 |
9.5 |
8.3 |
|
|
45 |
1196 |
50.5 |
9.6 |
8.3 |
|
|
40 |
829 |
50.4 |
9.6 |
8.4 |
|
|
35 |
521 |
50.1 |
9.8 |
8.7 |
|
|
30 |
285 |
54.7 |
9.8 |
8.6 |
|
|
25 |
135 |
54.8 |
9.4 |
8.9 |
|
|
20 |
41 |
58.5 |
8.2 |
6.3 |
|
|
15 |
9 |
77.8 |
6.8 |
7.5 |
|
|
10 |
2 |
100.0 |
5.3 |
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