[raiders72002]

Ganch, HELP

I lost my data and I'm looking for value of 1/2 pt at each different line.

[Ganchrow]

[moses millsap]

Ganch,

Do you have anything for adjustments in regular season total win props? For example, these 4:

9/1/2007 7:00 PM California regular season wins Wager is for regular season games only. Bowl and Conference Championship games not used in wager. Team must play all regular season games for action. Max wager $500
211 Over 9½ reg season wins +220
212 Under 9½ reg season wins -280

Where would you place the vig (with a 30c line) if we switched the total to 9 regular season wins?

9/1/2007 5:00 PM Florida regular season wins Wager is for regular season games only. Bowl and Conference Championship games not used in wager. Team must play all regular season games for action. Max wager $500
215 Over 10 reg season wins +320
216 Under 10 reg season wins -400

How about if this were to read 9 regular season wins (with 30c vig)?

8/30/2007 6:00 PM Rutgers regular season wins Wager is for regular season games only. Bowl and Conference Championship games not used in wager. Team must play all regular season games for action. Max wager $500
251 Over 10 reg season wins +220
252 Under 10 reg season wins -280

At 9.5 with 30c vig?

9/1/2007 11:00 AM West Virginia regular season wins Wager is for regular season games only. Bowl and Conference Championship games not used in wager. Team must play all regular season games for action. Max wager $500
269 Over 10 reg season wins -180
270 Under 10 reg season wins +150

At 10.5 with 30c vig?

[raiders72002]

Ganch- That is truly unbelievable. I've never seen a chart so comprehensive and user friendly. It's the most useful thing that I've ever seen on any forum.

What data did you use and from what years?

[Ganchrow]

Originally Posted by raiders72002

Ganch- That is truly unbelievable. I've never seen a chart so comprehensive and user friendly. It's the most useful thing that I've ever seen on any forum.

What data did you use and from what years?

Thanks. I appreciate that.

The data used is from Covers.com, and stretches back as far as the data was available for each sport with the exception of NFL. For NFL the data only goes back as far as the 1990-1991 season.

The data is only minimally transformed. I'm not currently adjusting for such changes in regime such as the advent of the NFL 2-point conversion in 1994 or the change in OT rules for NCAAF. I'm basically just following the Stanford Wong methodology, except I equal weight all games that lie the same distance from the target point spread or total.

I plan to improve on the sampling methodology in the very near future. Users retain the option to enter their own probability estimates.

[Ganchrow]

Originally Posted by OWNED

Ganch,

Do you have anything for adjustments in regular season total win props?

Although it may seem otherwise, the methodology for evaluating half-points in season win totals is actually rather different from evaluating half-points in spreads and game totals.

If you really wanted to come up with exact figures the first step would be to come up with win probability estimates for each game of the season, and then (either from first principles, or probably more easily using a Monte Carlo simulation) come up with estimates of winning any given number of games. Of course even that methodology would be flawed as there almost certainly exists some correlation between single-season game results.

Without considering individual match-ups, using the binomial distribution we can still come up with a first-order approximation of win total likelihood based solely on a single "fair" estimate of the likelihood of any given win total.

Using this methodology, I'll go to go through each of your examples one-by-one:

1. 9/1/2007 7:00 PM California regular season wins Wager is for regular season games only. Bowl and Conference Championship games not used in wager. Team must play all regular season games for action. Max wager $500
   211 Over 9½ reg season wins +220
   212 Under 9½ reg season wins -280
   
   Where would you place the vig (with a 30c line) if we switched the total to 9 regular season wins?

   A market of o9½ +220, u9½ -280 corresponds to a zero-vig over probability of 29.781%. Using Excel and Excel Solver, we see that a single-game win probability of 71.779% would correspond to a 29.781% probability of winning more than 9 games out of 12 (=combin(12,12)*71.779%^12 + combin(12,11)*71.779%^11*(1-71.779%)^1 + combin(12,10)*71.779%^10*(1-71.779%)^2 ≈ 29.781%).
   
   This then implies a 25.010% probability of winning exactly 9 games (=combin(12,9)*71.779%^9*(1-71.779%)^3 ≈ 25.010%), so a probability of going over 9 conditioned on not exactly 9 of 29.781%/(1-25.010%) ≈ 39.713%.
   
   A 39.713% corresponds to US odds of about +151.807 on the over.
   
   Given vig of 30c this corresponds to a market of approximately:
   o9 +140.73
   u9 -170.73
   

2. 9/1/2007 5:00 PM Florida regular season wins Wager is for regular season games only. Bowl and Conference Championship games not used in wager. Team must play all regular season games for action. Max wager $500
   215 Over 10 reg season wins +320
   216 Under 10 reg season wins -400
   
   How about if this were to read 9 regular season wins (with 30c vig)?

   A market of o10 +320, u10 -400 corresponds to a zero-vig (conditional) over probability of 22.936%. Using Excel and Excel Solver, we see that a single-game win probability of 75.802% would correspond to a 22.936% probability of winning more than 10 games out of 12, conditioned on not winning exactly 10.
   
   A 75.802% single-game win probability implies a probability of winning more than games of 41.589%, and of winning exactly 9 games of 25.757%. This corresponds to a conditional probability on the over 9 of 41.589%/(1-25.757%) ≈ 56.017%, corresponding to US odds of about -127.361.
   
   Given vig of 30c this corresponds to a market of approximately:
   o9 -145.12
   u9 +115.12
   

3. 8/30/2007 6:00 PM Rutgers regular season wins Wager is for regular season games only. Bowl and Conference Championship games not used in wager. Team must play all regular season games for action. Max wager $500
   251 Over 10 reg season wins +220
   252 Under 10 reg season wins -280
   
   At 9.5 with 30c vig?

   Over 10 conditional prob: 29.781%
   Single game conditional win prob = 77.857%
   Prob of > 9 games = 48.378%
   48.378% => US odds of ~ +106.705
   
   Given vig of 30c this corresponds to a market of approximately:
   o9½ -107.00
   u9½ -123.00
   

4. 9/1/2007 11:00 AM West Virginia regular season wins Wager is for regular season games only. Bowl and Conference Championship games not used in wager. Team must play all regular season games for action. Max wager $500
   269 Over 10 reg season wins -180
   270 Under 10 reg season wins +150
   
   At 10.5 with 30c vig?

   Over 10 conditional prob: 61.644%
   Single game conditional win prob = 84.800%
   Prob of > 10 games = 43.569%
   48.378% => US odds of ~ +129.523
   
   Given vig of 30c this corresponds to a market of approximately:
   o10½ +117.40
   u10½ -147.40

So anyway, that's it. I don't think I've made any silly computational errors, but it's always a possibility. I've sort of raced through, so if anything isn't clear, just ask.

[Scorpion]

Originally Posted by Ganchrow

Thanks. I appreciate that.

The data used is from Covers.com, and stretches back as far as the data was available for each sport with the exception of NFL. For NFL the data only goes back as far as the 1990-1991 season.

The data is only minimally transformed. I'm not currently adjusting for such changes in regime such as the advent of the NFL 2-point conversion in 1994 or the change in OT rules for NCAAF. I'm basically just following the Stanford Wong methodology, except I equal weight all games that lie the same distance from the target point spread or total.

I plan to improve on the sampling methodology in the very near future. Users retain the option to enter their own probability estimates.

Andy,
Why not save time and just copy Pinnacle? their data is much more accurate than covers

[RickySteve]

Originally Posted by Scorpion

Andy,
Why not save time and just copy Pinnacle? their data is much more accurate than covers

Don't post. Ever.

[Ganchrow]

Originally Posted by Scorpion

Why not save time and just copy Pinnacle? their data is much more accurate than covers

That's a non sequitur on par with octuplets.

[curious]

All of this ciphering is way over my head.

When I bet football I just make sure that the + is over the next combination of field goal / touch down. So, if the + is 3 I buy the 1/2 point to get 3 1/2, if the + is 5 I buy 2 1/2 points to bet 7 1/2...

If the points are -, i buy to get below the next combination. so if it was -8, i would buy 1 1/2...etc.

Can't tell you if this is the "best" thing to do mathematically. I just know that psychologically I would be a basket case if I didn't buy that extra 1/2 point and then lost a game because of it.

[homedog]

Buying points on a consistent basis will put you in the poor house.

[Ganchrow]

Originally Posted by homedog

Buying points on a consistent basis will put you in the poor house.

Well that's the whole purpose of the calculator ... it tells you approximately how much extra value you gain or losing by buying or selling one or more half-points.

[Ganchrow]

Originally Posted by curious

All of this ciphering is way over my head.

When I bet football I just make sure that the + is over the next combination of field goal / touch down. So, if the + is 3 I buy the 1/2 point to get 3 1/2, if the + is 5 I buy 2 1/2 points to bet 7 1/2...

If the points are -, i buy to get below the next combination. so if it was -8, i would buy 1 1/2...etc.

Can't tell you if this is the "best" thing to do mathematically. I just know that psychologically I would be a basket case if I didn't buy that extra 1/2 point and then lost a game because of it.

Take the NFL week 1 Pinnacle line, Tampa Bay +6 -106 at Seattle -6 -104. That's vig of 1.914%.

Take Tampa at 7½ and you'll be laying -151 at Pinnacle.

According to the half-point calculator, buying Seattle up to 7½ (paying -151) will cost you an extra 1.889% of vig for a total of 3.803%.

It is of course up to you to determine for yourself whether paying twice as much in vig is worth the possible basket case risk.