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Vegas And The SEC: More Proof That The Line Isn’t A Prediction

gfx - by the numbersIf there is one myth that we at MrSEC.com would like to bust it’s the belief that the Vegas line is a prediction by the Las Vegas oddsmakers of who will win a particular game.  It isn’t.  It never has been.  It never will be.

Yet millions of everyday fans view the Vegas line as a form of prognostication.  Media members — and we should flat know better — wonder openly about how the folks in the desert can like this team over that one.  And coaches use the line as motivation to their players: “They think that team’s 20 points better than you!”

In reality, the oddsmakers who set the initial opening line in Las Vegas each week are trying to come up with a perfect number that will lead as many people to bet on Team Y as on Team X.  That’s why the lines move throughout the week.  Once the LVSC (Las Vegas Sports Consultants) provides casinos with its opening lines, the numbers start moving based on the action coming in on each side.

The casinos simply want the same amount of money to come in on each team.  Ideally, the money made off of people who bet the loser will pay off all the people who bet the winner.  The casinos lose no cash in those kinds of transactions but they do get to keep the vigorish which is what the casinos charge gamblers to place a sports bet.

Let’s say you want to win $100 on a game.  You would need to bet $110 on Team Y to cover the spread and the casino would keep 10 of those dollars as the vig.  Now, let’s say I put $110 on Team X to cover the spread.  If Team Y wins, you get your $110 back plus $100 for the win.  Your winnings would come from me in this scenario, not from the casino because there was an even amount of cash bet on each team.  And the extra $10 bucks I put down?  The casino keeps that as the vigorish.

Still, the myth of the Vegas line continues.  When bowl season rolled ’round and SEC teams were favored in all nine of their bowl games, talkshow host after blogger after sportswriter incorrectly stated that the Las Vegas bookmakers really loved the SEC.  No.  Las Vegas bookmakers knew that the sports gamblers coming to Las Vegas in December would love the SEC.  Joe Q. Sportsfan knows that the SEC is dominant.  That average fan — the kind of guy who doesn’t bet every weekend — would therefore be more likely to put his money on Southeastern Conference teams.  From there, the spreads were moved until they were large enough to bring in an equal amount of dollars on the teams those SEC squads were facing.

This is remedial stuff for you gamblers out there.  And for those scoffers who refuse to accept the fact that the Vegas line is not a true prediction of who’ll win a game, pick up a book or do a Google search on the topic.  Heck, you can get started here, here, or here.  And the next step is to ignore it when you hear someone declare that “Vegas thinks we’ll win by 10.”

There’s also a myth within the myth that has convinced many people that the Vegas Line is a prediction.  “The guys in Vegas are always right on the number!”

Again, no, they’re not.  Oh, they’re often on the number regarding what digits will convince an even number of people to bet on both teams in a game, but they’re not as dead-on accurate as many believe when it comes to their opening lines.

During the 2012 season and the 2013 postseason, Southeastern Conference teams played a total of 122 football games.  There was an opening line for 103 of those contests.  Four opened as “pick ‘em” games and the other 15 had no Vegas line because the SEC teams were facing teams from the FCS.

For the sake of our exercise, we’ll toss out the “pick ‘em” and no-line games.  In the remaining 103 SEC contests, the opening odds from the LVSC were off by an average of 13.69 per game.  Yes, almost two touchdowns.  So much for, “the guys in Vegas always come close.”  That — like the point spread being a prediction — is a myth.  It only seems like the bookmakers are always close because we remember the times when they do hit the nail on the head.

For example, this year the opening line for South Carolina’s game with Kentucky had the Gamecocks favored by 21.  Turns out, Carolina won the game 38-17 by 21 points exactly.  Impressive.  Yet that was the only time all season the LVSC opening line matched the final point differential in an SEC game with the favored team winning.

Here’s a bit more for you to chew on…

 

Opening Line within 3 points or less of being correct:  11 of 103 possible games (10.6%)

Opening Line within 7 points or less of being correct:  29 of 103 possible games (28.1%)

Margin of victory 14 or more points off from the Opening Line:  49 of 103 possible games (47.5%)

Margin of victory 21 or more points off from the Opening Line:  24 of 103 possible games (23.3%)

 

In other words, the opening line was off by 21 or more points almost as many times as it was within a touchdown or less.  And the line was off by two TDs or more nearly half the time.

This isn’t to bash the bookmakers.  It’s to try and show you that they’re not even attempting to do what so many people out there think they are attempting to do.

Below are all 122 SEC games from 2012-13.  You can see who was favored, by how much, and how far off the opening line actually was at game’s end.

When the fall rolls around, maybe there will be a few less fans and media members running around saying, “Vegas thinks we’re gonna lose by 3!”

 

  Weekend   Game   Score   Difference from Opening Line
  Sept. 1   USC -8 vs VU   USC 17-13   4
  UT -7 vs NC State   UT 35-21   7
  UGA -37 vs Buffalo   UGA 45-23   15
  UF -23 vs Bowling Green   UF 27-14   10
  MU vs SE La (no line)   MU 62-10   –
  UM vs C. Arkansas (no line)   UM 49-27   –
  MSU vs Jackson State (no line)   MSU 56-9   –
  Clemson -3 vs AUB   Clemson 26-19   3.5
  ARK vs Jacksonville State (no line)   ARK 49-24   –
  LSU -48 vs N. Texas   LSU 41-14   21
  ALA -11 vs Michigan   ALA 41-14   16
  Louisville -13 vs UK   Louisville 32-14   5
  Sept. 8   MSU -s vs AUB   MSU 28-10   16
  USC -23.5 vs ECU   USC 48-10   14.5
  A&M -2.5 vs UF   UF 20-17   5.5
  ALA -37 vs W. Kentucky   ALA 35-0   2
  UT vs Georgia State (no line)   UT 51-13   –
  UM -4 vs UTEP   UM 28-10   14
  LSU -22 vs Washington   LSU 41-3   16
  ARK -28 vs La-Monroe   La-Monroe 34-31   31
  UK -7 vs Kent State   UK 47-14   26
  UGA -3.5 vs MU   UGA 41-20   17.5
  VU -1.5 vs Northwestern   Northwestern 23-13   11.5
  Sept. 15   AUB -17 vs La-Monroe   AUB 31-28   14
  VU vs Presbyterian (no line)   VU 58-0   –
  A&M -10 vs SMU   A&M 48-3   35
  ALA -13 vs ARK   ALA 52-0   39
  UF vs UT (pick ‘em)   UF 37-20   –
  USC -33.5 vs UAB   USC 49-6   9.5
  MU -7.5 vs Arizona State   MU 24-20   3.5
  MSU -13 vs Troy   MSU 30-24   7
  UK -4.5 vs W. Kentucky   W. Kentucky 32-31   5.5
  UGA -44.5 vs FAU   UGA 56-20   8.5
  LSU -43.5 vs Idaho   LSU 63-14   5.5
  Texas -13.5 vs UM   Texas 66-31   21.5
  Sept. 22   UM -15 vs Tulane   UM 39-0   14
  UF -23.5 vs UK   UF 38-0   14.5
  USC -9 vs MU   USC 31-10   12
  ALA -15 vs FAU   ALA 40-7   18
  ARK vs Rutgers (pick ‘em)   Rutgers 35-26   –
  LSU -18.5 vs AUB   LSU 12-10   16.5
  MSU 32.5 vs S. Alabama   MSU 30-10   12.5
  A&M vs SC State (no line)   A&M 70-14   –
  UT -35 vs Akron   UT 47-26   14
  UGA -16 vs VU   UGA 48-3   29
  Sept. 29   MU vs UCF (pick ‘em)   MU 21-16   –
  A&M -11.5 vs ARK   A&M 58-10   36.5
  UGA -15.5 vs UT   UGA 51-44   8.5
  USC -21 vs UK   USC 38-17   0
  LSU vs Towson (no line)   LSU 38-22   –
  ALA -33 vs UM   ALA 33-14   14
  Oct. 6   AUB -10.5 vs ARK   ARK 24-7   27.5
  MSU -14.5 vs UK   MSU 27-14   1.5
  LSU -2.5 vs UF   UF 14-6   10.5
  A&M -12.5 vs UM   A&M 30-27   9.5
  USC -2.5 vs UGA   USC 35-7   25.5
  MU -6.5 vs VU   VU 19-15   10.5
  Oct. 13   UM -1 vs AUB   UM 41-20   20
  ALA -17.5 vs MU   ALA 42-10   14.5
  UF -8.5 vs VU   UF 31-17   5.5
  ARK -16 vs UK   ARK 49-7   26
  LSU -4 vs USC   LSU 23-21   2
  MSU -1.5 vs UT   MSU 41-31   8.5
  A&M -6 vs Louisiana Tech   A&M 59-57   4
  Oct. 20   LSU -3 vs A&M   LSU 24-19   2
  VU -9 vs AUB   VU 17-13   5
  UF -3.5 vs USC   UF 44-11   29.5
  ALA -18.5 vs UT   ALA 44-13   12.5
  UGA -27 vs UK   UGA 29-24   22
  MSU -20 vs MTSU   MSU 34-3   11
  Oct. 27   MU -15 vs UK   MU 33-10   8
  USC -14 vs UT   USC 38-35   11
  ARK -4.5 vs UM   UM 30-27   7.5
  UF -3.5 vs UGA   UGA 17-9   11.5
  A&M -7 vs AUB   A&M 63-21   35
  VU -34 vs UMass   VU 49-7   8
  ALA -24 vs MSU   ALA 38-7   7
  Nov. 3   UF -16 vs MU   UF 14-7   9
  A&M -2.5 vs MSU   A&M 38-13   22.5
  VU -9 vs UK   VU 40-0   31
  UT -20.5 vs Troy   UT 55-48   13.5
  ARK -5.5 vs Tulsa   ARK 19-15   1.5
  AUB -23 vs N. Mexico State   AUB 42-7   12
  UGA -17.5 vs UM   UGA 37-10   9.5
  ALA -7 vs LSU   ALA 21-17   3
  Nov. 10   USC -15.5 vs ARK   USC 38-20   2.5
  UT -2.5 vs MU   MU 51-48   5.5
  UF -27 vs La-Lafayette   UF 27-20   20
  ALA -16 vs A&M   A&M 29-24   21
  UGA -16 vs AUB   UGA 38-0   22
  LSU -17 vs MSU   LSU 37-17   3
  UM -1 vs VU   VU 27-26   2
  Nov. 17   MSU -6 vs ARK   MSU 45-14   25
  ALA vs W. Carolina (no line)   ALA 49-0   –
  UF vs Jacksonville State (no line)   UF 23-0   –
  USC vs Wofford (no line)   USC 24-7   –
  AUB vs Alabama A&M (no line)   AUB 51-7   –
  UGA vs Ga. Southern (no line)   UGA 45-14   –
  LSU -20 vs UM   LSU 41-35   14
  A&M vs Sam Houston State (no line)   A&M 47-28   –
  VU -2 vs Tennessee   VU 41-18   21
  MU -6.5 vs Syracuse   Syracuse 31-27   10.5
  UK vs Samford (no line)   UK 34-3   –
  Nov. 24   LSU -13.5 vs ARK   LSU 20-13   6.5
  UGA -14 vs Georgia Tech   GA 42-10   18
  UT -14 vs UK   UT 37-17   6
  ALA -34 vs AUB   ALA 49-0   15
  Florida State -7 vs UF   UF 37-26   18
  VU -8.5 vs Wake Forest   VU 55-21   25.5
  A&M -16.5 vs MU   A&M 59-19   23.5
  MSU vs UM (pick ‘em)   UM 41-24   –
  Clemson -4 vs USC   USC 27-17   14
  SEC Title   ALA -7.5 vs UGA   ALA 32-28   3.5
  Bowls   VU -5 vs NC State   VU 38-24   14
  LSU -3 vs Clemson   Clemson 25-24   4
  MSU -2 vs Northwestern   Northwestern 34-20   16
  USC -4.5 vs Michigan   USC 33-28   0.5
  UGA -8.5 vs Nebraska   UGA 45-31   5.5
  UF -15 vs Louisville   Louisville 33-23   25
  A&M -3 vs Oklahoma   A&M 41-13   25
  UM -2 vs Pittsburgh   UM 38-17   19
  ALA -9.5 vs Notre Dame   ALA 42-14   18.5

 

In case you’re wondering, if you’d bet on the favorite to cover in the 103 SEC games that opened with a point spread, you’d have gone 57-46 (55.3%) in 2012-13.

 


3 comments
compliceancien
compliceancien

And pennington shows why non-math people should not attempt to write about mathematical topics...

 

A vegas line absolutely, 100% IS a prediction, and is the best one known to mankind (particularly the money line, spread is a little more indirect).  Yes, he is correct that it moves to balance the wagers so that losers balance winners and the house gets the vig.  But in doing so, it induces the number that best reflects all available information (see Efficient Markets Theory from economics).  

 

He can be forgiven for saying that 'vegas' is not making the prediction, because that's true.  The opening line is a prediction of what the line will ultimately be, but if you use the term 'vegas' to mean 'all the money folks are wagering worldwide' and where the line ends up then yes, 'vegas' is making a prediction.

 

His breakdown of how results differed from spreads is laughable.  What is he comparing those results to?  F*** all!  So if it's not a predicition, what is the more accurate predictor?  Sagarin?  ELO Chess?  W-L?  Any statistical measure under the sun?  NO, the answer is NOTHING is a better predictor.  If there is a better one that actually beats vegas over a long period of time, please show it to me.  But please don't show it to anyone else, because you and I have some money to make.

BonzaiB
BonzaiB

The entire time I was reading this, I was wondering what Mr Pennington does with his spare time, cause it would have taken me a week to write this.

 

It will take me another week to understand it. Pretty sure I will have the first paragraph nailed by bedtime.....

John at MrSEC
John at MrSEC moderator

 @compliceancien 

 

What an ugly post.  

 

I would nuke it, but I like for people to see the kind of trash we get for providing free information.  Information, in this case, that can be gathered from books, one-on-one interviews with Las Vegas casino bookmakers (which we've done for three different summer pieces on Vegas and the SEC), intelligent gamblers, various gambling sites, or even a major sports news service like Yahoo! Sports.com:  http://rivals.yahoo.com/ncaa/football/odds.

 

I will say this regarding our "laughable" breakdown of the spreads -- we weren't comparing the results to anyone.  We were trying to show people who routinely say, "The guys in Vegas are always dead-on" that, in fact, they're not.  Unless you consider being off by an average of two touchdowns per SEC game "dead-on."  Are they better than most?  Maybe.  But that doesn't change the fact that the myth of Vegas' accuracy with regards to point differentials is just that... a myth.

 

Enjoy your day,John 

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