# Math Question - How to calculate value in this play?

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 Author Topic: Math Question - How to calculate value in this play?  (Read 1336 times)
myst
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« on: November 30, 2016, 07:59:19 AM »

Book 1:
To Score a Touchdown
Player A: -150 Yes, +110 No
Player B: -150 Yes, +110 No

Book 2:
Who will score more touchdowns? (2-way, push on tie)
Player A: +120
Player B: -160

Since the two books' value of each player are way off, and assuming we are not experts at picking out which is the soft line, is there a way to surebet this between the 2 books? How do we extract the most EV?
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Gamblers Ruin
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« Reply #1 on: November 30, 2016, 11:42:28 AM »

At first glance I don't think there is even value here, but you certainly can't surebet it because:
• If neither player scores your second bookie's bets get pushed, so your book 1 NO-NO bets need to cover all stakes from book 1
• If both players score once, again your second bookie's bets get pushed, but you need YES-YES from book 1 to cover all stakes from book 1
The above cannot both be true, as your book 1 odds are symmetrical and not arbs
 « Last Edit: November 30, 2016, 03:30:58 PM by Gamblers Ruin » Logged

Win->bet more->lose->bet same-> bankrupt
myst
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« Reply #2 on: November 30, 2016, 06:29:06 PM »

Ah I see, you make a good point, thank you. Wouldn't there have to be value somewhere though, since one book has them at 1:1 odds against each other, and the other book has one at almost 2:1?
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barbero
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« Reply #3 on: November 30, 2016, 09:35:32 PM »

As long as there are big enough differences in odds between two bookies, there would have to be value in at least one of them, right? How to find in which side, that's the point
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Gamblers Ruin
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« Reply #4 on: December 01, 2016, 10:37:12 AM »

As long as there are big enough differences in odds between two bookies, there would have to be value in at least one of them, right? How to find in which side, that's the point
I think this is generally true, but in this case the 2 markets are quite different. It's actually possible for both bookies to be 100% sharp here and zero value, because of weird stuff in sport like "if player A scores, then player B is more likely to score twice" etc.

Book 1 is saying 56% No, 44% Yes on both players.
Book 2 is saying the chance of B>A is 1.35X the chance of A>B, whatever they may be.

Both books can be 100% sharp if these are the probabilities:

 - - - Player B Touchdowns - - - 0 1 2 - 0 19.58% 24.67% 0% Player A Touchdowns 1 24.67% 22.35% 8.73% - 2 0% 0% 0%

Conclusion: there may be value here just like anywhere, but only if you know more than the bookies. Yay for maths!
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barbero
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« Reply #5 on: December 01, 2016, 12:47:45 PM »

That's right, in such cases some knowledge of the particular sports necessarily kicks in. I tend to be skeptic about "if player A scores, then player B is more likely to score twice" kind of statements (meaning I'm not all that sure that's true... but the way to go should be checking that statement's accuracy with some past stats). In any case, I agree with your point: couples of bet types that are correlated but not totally the same might allow for situations where odds seem to differ a lot, but there is actually no value.
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Gamblers Ruin
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« Reply #6 on: December 01, 2016, 01:37:50 PM »

lol my example was ridiculous, the idea was just that the two players scoring touchdowns are not independent.

If you're worried, this also satisfies all the criteria without being insane. If this is the case, both bookies have picked their odds perfectly:

 - - - Player B Touchdowns - - - 0 1 2 - 0 19.58% 14.67% 10% Player A Touchdowns 1 24.67% 22.35% 8.73% - 2 0% 0% 0%
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Win->bet more->lose->bet same-> bankrupt
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