Category: Betting Advice

What’s More Likely? Part 1

This is the first in a multi-part series of posts where we look at whether a characteristic about a game has any relationship to which team will cover. In this post, we will explore whether the favorite or the underdog is more likely to cover the spread. To do this, we will work with the data set of college basketball games to determine whether the favorite or underdog is more likely to cover the spread.

First, some high level statistics. In the 22,215 games, the favorite covered 49% of the games, the underdog covered 48.9% of the games and 2.1% of games ended in a push (i.e., the outcome of the game matched the spread and neither team covered). So, neither the favorite or the underdog is more likely to cover the spread all else equal.

Is the Home Team More Likely to Cover the Spread?

No. In the 16,039 games the home team was favored they covered the spread in 8,037 games (50.1%). Conversely, the away underdog covered 8,002 spreads (49.9%). In the 5,713 games the home team was an underdog they covered the spread in 2,821 games (49.4%) and the away favorite covered 2,892 games (50.6%). In 463 games the spread resulted in a push.

So the home team is more likely to be favored but no more likely to cover than an away underdog. And the home underdog is no more likely to cover than the away favorite. So no pattern here…

Does the Size of the Spread Matter?

Another reasonable consideration is the size of the spread. Let’s see if a big favorite is more or less likely to cover the spread?

Putting the size of the spreads into 10 bins, we see no pattern.

  • A 1 point favorite has a 51% chance to cover the spread
  • A 16 point favorite has a 50.4% chance to cover the spread.

So no pattern here either….

Spread Range Favorite Covers Underdog Covers Favorite Covers %
-1 to -1.5 813 778 51.0%
-2 to -2.5 1,045 1,050 49.9%
-3 to -3.5 976 994 49.6%
-4 to -5 1,404 1,401 50.0%
-5.5 to -6 905 858 51.3%
-6.5 to -7.5 1,202 1,214 49.8%
-8 to -9.5 1,249 1,262 49.7%
-10 to -12 1,092 1,132 49.1%
-12.5 to -15.5 1,079 1,054 50.6%
-16 or more 1,135 1,115 50.4%

There are many more factors that could contribute, but from the data available, we can conclude that neither playing at home, on the road, with a large spread or a small spread has any relationship to whether a team covers the spread.

You Might Want to Moneyline an Underdog

The team you want to bet on is 3.5 point underdogs. You have two choices, you can take the points and bet on the spread or you can take your underdog to win outright and bet on the moneyline. Typically taking the points will require you to wager $110 to win $100 (110/100) depending on the vig. The moneyline bet will give you odds, paying $150 for risk $100 (100/150).

What should you do? Take the moneyline bet every time.

Why? Because the expected value of the moneyline bet is significantly higher than the spread bet. Since we’ve already decided to bet on the underdog, what we need to know is what the percentage of the time that the 3.5 point spread will come into play, that is the underdog will lose the game by 3 points or fewer, resulting in the underdog covering the spread but losing the game. Then we need to determine whether the moneyline risk reward compensates us enough to offset the additional risk.

A few statistics from our basketball data set, specifically the 1,025 games with a 3.5 point spread. Side note – a 3.5 point spread is one of the most common type of spreads in college basketball.

  • The underdog won 409 games (39.9%)
  • The underdog covered the spread in 528 games (51.5%)
  • The underdog covered the spread but lost the game in 119 games (11.6%)

Using these facts, the expected outcome of each bet is calculated below.

  • Underdog Spread = -$1.74
    • (.515*100)+(.484*-110)
  • Underdog Moneyline = -$.85
    • (.393*150)+(.607*-100)

As you can see, the expected payout is for both bets is negative. Sports books wouldn’t be in business over the long run if they set positive payout scenarios. But more importantly, the moneyline expected payout is $.89 higher. While this doesn’t seem like much, it’s worth noting that card counting at Blackjack raises the payout per $100 wagered from -$1 loss to a $1 game or a difference of $2. This same strategy which takes no work increases your expected payout by 45% of the advantage card counting gets you. You may also note that the moneyline odds could be +155 or +160 for this line which would increase your payout.

A few notes

  • The spread and the moneyline, while related, do not always move in lockstep. For the above example, I could find instances where a 3.5 point spread was listed for moneyline odds at +145 to +165 and this plays an important part in the analysis with the greater the payout increasing the appeal of moneyline.
  • A different and less formulaic way to think about this problem is to think about the percentage of time you will lose a moneyline bet but would have won the spread bet. In this instance, we know these odds – 11.6%. You are risking around 50% more betting spreads instead of moneyline to win 11.6% more wagers.
  • This same logic holds for betting on a favorite with the moneyline in this example. However, analysis has shown that this rule is much less likely to hold at other odds. View this post for more details.
    • Favorite Spread = -$8.25
      • (.484*100)+(.515*-110)
    • Favorite Moneyline = -$6.11
      • (.393*-170)+(.607*100)