teaser probabilites

**Justin7** · 09-26-09, 10:13 AM

Decimal probability is simply 1 + 10/12.. or 1.83.

**arwar** · 09-26-09, 10:53 AM

that's not what I meant.

assume Ohio State -14 v Illinois is a 50/50 proposition = .5 or 1/2
then what is p1(Ohio State -7) (2 team), p1(-4) (3 team), and p1(-1) (4 team)

then do you multiply p1*p2 and p1*p2*p3 and p1*p2*p3*p4?

if so how do adjust for the juice?

**Justin7** · 09-26-09, 12:31 PM

If a 2-team parlay pays 1.83, each individual leg pays square root (1.83), or 1.353 in this case.

A 3 teamer would use the third root, and a 4-teamer would take the 4th root.

**arwar** · 09-26-09, 06:45 PM

it's not a parlay in the sense that it doesn't pay some multiple i.e. 13:5; it is a teaser that pays 100 or loses -120 on the play.

the probability of the play has to be less than or (unlikely but) possibly equal to 1.

using Penn State as an example for the first leg and ignoring the vig then presumably the probablty of PSU-14 is p(PSU-14)= .5; also p(IOWA+14)= .5

so how do you calculate their p on the 2 teamer where they get 7?? p(PSU-7)?
maybe p(PSU-7)= .75; then p(IOWA+7)= .25 ????? how do you calculate the .75 (or whatever it is) ?

and then a 3 teamer p(PSU-4)
and a 4 teamer p(PSU-1)

then repeat the process for each leg of the play and then what? p(OSU)*p(2)??? and then adjust for the vig?

**RickySteve** · 09-26-09, 07:15 PM

Pretty good thread.

**Ominous** · 09-27-09, 09:27 AM

You have to go by push frequencies. Each point you buy will increase your teams chance of covering by a certain %age. Halfpoint calculator is a good place to start but it wastly overestimates the push freq for points far away from the actual spread.

Hint. No way in hell there is value in a two team -120 teaser from -14 to -7

**arwar** · 09-27-09, 10:39 AM

i am not sure that i agree with the assertion that there is no value in a 2 team 7 point teaser at -120. Maybe NCAAF was a bad example, it seems intuitive that 7,10,13 points are worth more in the NFL than college where o/u routinely hit 60+. On a 3 team parlay paying a street price of 5X (which I never play btw) I figure the probablity is .5*.5*.5=.125 or (1/2)(1/2)(1/2)=1/8. This means that there is one winnng combination out of 8 possible outcomes. If a player were to play $6 on each of the possible outcomes then 7 would lose for $42 and one would win for $30. This means that $48 is being booked and $36 paid out resulting in a vig of 25% or a sucker play. {in this example assuming the 1/2 are fair what is the actual prob considering the vig?}
My queston about the teaser is how to do an analysis like this one for the parlay?
If a team at -14 has a .5 probability of winning how can I adjust that probabilty value if the line moves to -1. I am a very fast programmer and if somebody gives me the psuedo-code (i.e. logic) of the data I need to extract, etc. I can write a routine to do it in a couple of hours.

as far as the value in a 2 team 7 pointer, I know one fellow in particular who does very well with them. teasers are fun especially when you have 3 or 4 live ones with open slots.

**Ominous** · 09-28-09, 06:59 AM

Basically the 3 is the key, its worth almost twice as much as the 7. Go check the halfpoint calculator, (it overestimates the value of buying points far from the spread) but even with the halfpoint calc you find than when buying from 14 to 7 in NFL the true odds implied by halfpoint calculator is
-7 -215 +7 +215. Your two team teaser of -120 corresponds to a one team odds of -283.

**calm** · 09-29-09, 01:54 PM

Mmm decimal odds.