Why +EV isn't everything (points available)

[WeinketoWarrick]

If someone told me I had to risk everything on a +110 or would get infinite bets for 2.5% the amount at +102.5, of course I'm going to bet the +102.5 for the rest of my life and be a happy, rich man.

But that isn't the example.

[YouMama]

But you said a "single" coin flip.

exactly... and since u figuring all this other stuff, why not just go for broke and figure in the most valuable x-factor there is... time... what if I pass up option one, go with option 3, win 4 bets and die? ... well then I just F'ed myself didnt I.

[FourLengthsClear]

You went from a single bet to multiple bets.

Even though it is only a single bet you are offered, thinking about it as the first of a series of identical bets is the only way to evaluate the risk of ruin.

[Grits n' Gravy]

The answer should always be c. Consider the example a sporting event that is a basically a coin flip kind of game where you don't have a strong argument for either side. Do you go all in on a game like that? No. These kind of plays you either pass or play small and grind out profits to put bigger bets on plays you feel strongly about.

[135steward]

huh?

I think the original example assumes you are a gambler, and the coin flip is one of many different types of bets you are offered during your gambling career.

Those bets aren't offered in the example. I'd take forsberg's 2:1 offer over 4LCs. But it wasn't offered in the original example.

[WeinketoWarrick]

I don't need to pretend it's the first in a series to know option A involves more risk.

If I know I'll be getting a series of the same opportunities then the answer changes.

But you said one bet.

Changing the scenario and implying multiple future bets with the same limits and value makes it a different question and leads to a different answer.

[135steward]

!

The answer should always be c. Consider the example a sporting event that is a basically a coin flip kind of game where you don't have a strong argument for either side. Do you go all in on a game like that? No. These kind of plays you either pass or play small and grind out profits to put bigger bets on plays you feel strongly about.

Not even close. We're giving the book the 110/100 advantage. For the Kelly crew, that means no bet at all.

[Grits n' Gravy]

Question. Don't many games in Vegas hold higher than their theoretical % advantage because of this bankroll issue? Does this include slot machines? I'm not certain this is the case but I thought I read that or saw it on tv.

Yes and no. Tables hold can be volatile on baccarat, craps and blackjack when real big players throw down. Games like 3 card poker and the rest you now see with greater prescence on casino floors are there because they hold 30% give or take year over year. Slots are a different animal as is video poker. Machines may hold higher than their theoretical for a variety of reasons. Over time they balance out. Video poker actual hold vs. theoretical hold will vary mainly off player skill. A bad player who plays big can take a machine that should have a 3% house edge and turn it into a 7% hold just by playing dumb. Conversely a skilled player with a good bankroll can turn a machine upside down if they play smart and catch a few cards.

[FourLengthsClear]

I don't need to pretend it's the first in a series to know option A involves more risk.

If I know I'll be getting a series of the same opportunities then the answer changes.

But you said one bet.

Changing the scenario and implying multiple future bets with the same limits and value makes it a different question and leads to a different answer.

I did say one bet and it still one bet.

What the EG formula tells us is whether, mathematically speaking, the quantum of the positive expected value of the bet is enough to justify the risk of ruin.

[Grits n' Gravy]

Not even close. We're giving the book the 110/100 advantage. For the Kelly crew, that means no bet at all.

I get your point and the example I was using should have said you are getting +money on a game that is essentially a pick em where you can't play the other side at +money as well to scalp.

[BettingWizard]

if you never reload, 3 is the best option. option 2 you're getting 100% better odds, but you have to risk 500% more

[WeinketoWarrick]

Math can never tell you if something is worth the risk of ruin. Never.

It can tell you how you'll be ruined, how quickly it will occur, and how you could prevent it, but a formula will never be able to decide for each individual if the risk is worth the reward.

"You can't win what you don't put it in the middle"

[RudyRuetigger]

1. apparently most here didn't read my link
2. apparently most here have no idea how kelly criterion works and therefore has no idea how to bet
3. apparently everyone who chooses answer A goes all in every time on a sports bet they have the same edge listed in OP. Somehow I don't think thats the case

[Romanov]

Considering expected growth you choose Option 3

[FourLengthsClear]

Math can never tell you if something is worth the risk of ruin. Never.

It can tell you how you'll be ruined, how quickly it will occur, and how you could prevent it, but a formula will never be able to decide for each individual if the risk is worth the reward.

"You can't win what you don't put it in the middle"

Interesting point of view.

Just as a matter of interest, would you accept that there is a correct/optimal amount to wager on each of the three options?

[Romanov]

Interesting point of view. Just as a matter of interest, would you accept that there is a correct/optimal amount to wager on each of the three options?

8.3%, 4.5% and 2.4%

[WeinketoWarrick]

Rudy, I never go all in. It doesn't mean "A" isn't the correct answer for those truly committed to getting the most for their money given the described "single bet" scenario.

4LC, I would not. Or else I don't understand your question. If I knew I had a 2.5% edge on every single bet I was making, I'd risk more than 2.5% of my bankroll on each bet. Probably more like 5% for myself. It's different for everybody based on how much gamble they have in them.

[FourLengthsClear]

Rudy, I never go all in. It doesn't mean "A" isn't the correct answer for those truly committed to getting the most for their money given the described "single bet" scenario.

4LC, I would not. Or else I don't understand your question. If I knew I had a 2.5% edge on every single bet I was making, I'd risk more than 2.5% of my bankroll on each bet. Probably more like 5% for myself. It's different for everybody based on how much gamble they have in them.

Fair enough but there are optimal amounts (that will generate the best results over time) for any bet where the edge is known. For a +105 coinflip, it is 2.4% (as romanov said in the post above yours). At anything more than 4.74% the long term expectation is negative (i.e. you will go broke eventually).

Good discussion though.

[WeinketoWarrick]

Eventually.

I don't plan to gamble until the end of time.

[JohnGalt2341]

There is a lot of discussion in PT about EV (expected value), what constitutes +EV and the obvious benefits of finding bets that have +EV. What does it really mean though? Suppose you have a bankroll of USD 10,000 and I offer you three options for a single bet on a (fair) coinflip. 1) I offer you odds of +120 (+EV of 10.0%) but you must wager all of your bankroll. 2) I offer you odds of +110 (+EV of 5.0%) but you must wager 10% of your bankroll 3) I offer you odds of +105 (+EV of 2.5%) but you must wager 2% of your bankroll Which one(s) of these would be a smart bet and why?

This is a great question. I would personally choose #3 mostly because I'm extremely tight and I almost never bet more than 3% of my bankroll.

I have a question for FourLengthsClear... What odds would you have to offer in order to make the first answer the right choice? Even I was getting +500 I still wouldn't bet my entire Bankroll on a coin flip.

[FourLengthsClear]

This is a great question. I would personally choose #3 mostly because I'm extremely tight and I almost never bet more than 3% of my bankroll.

I have a question for FourLengthsClear... What odds would you have to offer in order to make the first answer the right choice? Even I was getting +500 I still wouldn't bet my entire Bankroll on a coin flip.

Strictly speaking, never. According to the math, you should only put 100% of your bankroll in play if you have 100% probability of winning.

[jstblaze]

Four lengths,

I just wanted to confirm, that there is not really any option of opinion, there is only the one correct answer?

I do understand an outlying individual could win more using a different strategy (for example because they are the luckiest man in the world) but they would still be an outlier.

the only way to consistently beat the books is to do it by the numbers.

[Romanov]

Eventually. I don't plan to gamble until the end of time.

You are missing the point. Eventually it will catch up to you, and that day could start tomorrow

[Straight Cash]

Here's another good thread on Expected Growth.

http://forum.sbrforum.com/handicapper-think-tank/29841-maximizing-expected-growth-kelly-criterion-part-ii.html

[UntilTheNDofTimE]

Here's another good thread on Expected Growth. http://forum.sbrforum.com/handicappe...n-part-ii.html

Yup Ganchrow was like a lost leader

[broadway6]

Fair enough but there are optimal amounts (that will generate the best results over time) for any bet where the edge is known. For a +105 coinflip, it is 2.4% (as romanov said in the post above yours). At anything more than 4.74% the long term expectation is negative (i.e. you will go broke eventually).

Good discussion though.

i assume you mean 4.74% of your bankroll?

[HeeeHAWWWW]

This is a great question. I would personally choose #3 mostly because I'm extremely tight and I almost never bet more than 3% of my bankroll.

That's not remotely tight, it's nearly full Kelly!

The options are for:


1) Does it for the rush, will go bankrupt very quickly

2) Over-staker. Will go bankrupt eventually because >2x Kelly has neg expected bankroll growth. Even the best gambler in the world, 8% Roi, 15% Roi, 20%, whatever, this sort of staking is the road to ruin.

3) Aggressive player, high risk, potentially high reward.

[opie1988]

Four Lengths.....

Before I give my answer on your wager question, let me ask you this.....how quickly can I reload my account afterwards?

[FourLengthsClear]

Four Lengths.....

Before I give my answer on your wager question, let me ask you this.....how quickly can I reload my account afterwards?

Assume you can't.

[WeinketoWarrick]

You are missing the point. Eventually it will catch up to you, and that day could start tomorrow

I'm not missing the point.

The original question stated there was one opportunity to make one of the wagers listed.

Assuming all gamblers are looking to maximize profit and are willing to risk their entire bankroll to do so, A is the correct answer. DO NOT ASSUME that you'll be able to continue making 2.5% of your bankroll bets with an edge. This is a false assumption that misleads any mathematical calculations.

Now, does that mean everybody should go all in when they think they've got a big edge? Hell no. I would never do that, and I've had plenty of opportunities. But from a strictly "You have ONE bet to make, what's +EV?" theoretical standpoint, put it all on black, take your +120 if you win, and go retire with more than double what you had before, never to make another bet again.

Gamblers have a hard time answering this question truthfully because we're all degenerates that can't imagine making one and only one wager.

[FourLengthsClear]

i assume you mean 4.74% of your bankroll?

Yes.

[Romanov]

*** +EV bet

Line crashed to 7.5 at pinny and was still 8.5 at some shops on the Celtics/Bulls game

[broadway6]

There is a lot of discussion in PT about EV (expected value), what constitutes +EV and the obvious benefits of finding bets that have +EV. What does it really mean though?

Suppose you have a bankroll of USD 10,000 and I offer you three options for a single bet on a (fair) coinflip.

1) I offer you odds of +120 (+EV of 10.0%) but you must wager all of your bankroll.
2) I offer you odds of +110 (+EV of 5.0%) but you must wager 10% of your bankroll
3) I offer you odds of +105 (+EV of 2.5%) but you must wager 2% of your bankroll

Which one(s) of these would be a smart bet and why?

one more stupid question. how do you figure this out?

[broadway6]

*** +EV bet

Line crashed to 7.5 at pinny and was still 8.5 at some shops on the Celtics/Bulls game

this is someone who gambles like me

[Salmon Steak]

Because there isn't any +EV and we want to gamble.