Ganchrow Math ?

tacomax · 10-23-06, 07:31 PM

I'll divulge a bit of a SBR secret here. I actually do all of this maths stuff for Ganchrow since it's a bit over his head and I let him post it under his username. I've PM-ed him the answer to your query and hopefully he'll pick it up and then copy & paste it into this thread later on.

Justin7 · 10-23-06, 07:43 PM

Convert your teaser to decimal odds, call it P (payoff). At -220, P=1.68.

If X is the break-even decimal odds for each leg of a teaser (which would be 1.41 for a 2-team 6-pt teaser at +100) and Y is the number of legs,

X^Y=P

for a 9-teamer paying -220,
X^9 = 1.6875
X=1.06

The break-even payout on each leg is 1.06. That is equivalent to -1670 for each leg.

RickySteve · 10-23-06, 08:45 PM

Wow.

Doug · 10-23-06, 10:03 PM

Originally posted by Justin7

Convert your teaser to decimal odds, call it P (payoff). At -220, P=1.68.

If X is the break-even decimal odds for each leg of a teaser (which would be 1.41 for a 2-team 6-pt teaser at +100) and Y is the number of legs,

X^Y=P

for a 9-teamer paying -220,
X^9 = 1.6875
X=1.06

The break-even payout on each leg is 1.06. That is equivalent to -1670 for each leg.

RX guy has a different answer !

10-23-2006, 07:37 PM #8
Data
RX Junior

Join Date: Sep 2004
Posts: 254

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Open Windows Calculator, click View and select Scientific.
(220+100)/220=1.4545454545454545454545454545455
click x^y button, input 0.111111111111111111111111111111,
that is 1/9. Press Enter. You get 1.0425113954240645689425284621691. Substract 1, you get 0.0425113954240645689425284621691. Divide by 100 and then click on 1/x button. You get 2352.3104570543610721370178935887. So, the line is -2352.

SBR_John · 10-23-06, 10:05 PM

Uhhh... I think I need to find a square thread.

patswin · 10-24-06, 10:09 AM

Way above my head here

Ganchrow · 10-24-06, 12:05 PM

Originally posted by Doug

How do you figure this out ?

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What is the formula to figure out the juice you are paying on each leg of this, say a 9 team teaser ( -220) getting 21 points, what is each leg at ?

21 Points Football
3 Teams -2000
4 Teams -800
5 Teams -500
6 Teams -400
7 Teams -300
8 Teams -260
9 Teams -220
10 Teams -200
11 Teams -180
12 Teams -160
13 Teams -140
14 Teams -120
15 Teams 100
Ties Push

Do you have an easy way to figure this ?

There is no way to answer this question from first principles alone. A teaser is nothing more than a parlay of multiple bets on which points are purchased. As such, to figure out the juice on a teaser the first step would be calculating the true value of the purchased points.

The methodology for calculating this value is in theory no different from the methodology in play when calculating the value of a half-point (see the sticky threads at the top of the NCAA FB and NFL forums) on a any spread bet. In practice, however, the more points purchased the greater the importance of the magnitude of the total (and indeed the importance other factors not so easily encapsulated in a single number) in calculating the teaser value.

That said, by considering the payoffs for a given teasers, one can determine the required probability with which each leg would need to win in order to break even on average. Justin illustrates this particular methodology in his post above (taking the reciprocal of the final breakeven decimal odds gives you the breakeven probability) although he mistakenly converts a line of -220 to decimal odds of 1.68. In reality a line of -220 translates to decimal odds of about 1.45 not 1.68 (check out the odds converter to verify) -- nevertheless, the methodology he outlines is entirely accurate. Using the corrected decimal odds, the breakeven money line works out to be about -2,353, corresponding to a (geometric) mean probability of 95.92% per leg.

(I should point out that because the probability of the coincidence of independent events is multiplicative, the calculated breakeven probability is not an arithmetic mean, but rather a geometric one.)

Justin7 · 10-24-06, 01:27 PM

Originally posted by Ganchrow

Justin illustrates this particular methodology in his post above (taking the reciprocal of the final breakeven decimal odds gives you the breakeven probability) although he mistakenly converts a line of -220 to decimal odds of 1.68. In reality a line of -220 translates to decimal odds of about 1.45 not 1.68

I don't proof-read one post, and my reputation goes to hell.

Thanks for catching this, Ganchrow. I'd hate for SBR to get blamed for giving bad math advice

Doug · 10-25-06, 09:10 AM

So is -2353 a fair price to move an NFL line 21 points ?

I have nothing to compare it to, with 21 point NFL favs being so rare.

For CFB, Pinny has Utah -20, -1800 ( 44 total). I think the upset is more likely in college than NFL.

I guess the -2353 is about right, you'd have to hit 70% of these nine teamers to start being profitable.

Looking at teasing 21 point favs to pick isn't right either, as it would be more like taking +3.5 dogs to +24.5.

It's good to learn how to figure this though. I don't think I'll actually play these.