Optimal bet size question

[d2bets]

Suppose I am given 200-1 odds and I have a 1.00% chance to win.
What % of my bankroll should I bet on each wager?
I looked at the Kelley calculator, but I've never done that before and I'm not sure I'm doing it right.
It appears to say 0.505%. But is that right? Sounds like too much since I'd go broke after 200.

[Bostongambler]

Dbets, I know you so are you trying to trick us?

200-1 odds and you are putting it at 1.00% chance to win??? Or are you saying it is pre set so that it is 1.00% chance to win? 🤔


If it’s 200-1 odds, then yes 0.50 chance, no?

[Optional]

That sounds about right if playing full kelly.

Imagine if you think that 200-1 shot has more like a 5% chance to win. Would be over 4%

[jjgold]

d2 do not complicate this

stick to the 1.5 or 2 percent rule

[pologq]

how do you know it is 1% guarantee?

[d2bets]

That sounds about right if playing full kelly.

Imagine if you think that 200-1 shot has more like a 5% chance to win. Would be over 4%

OK, thanks. It "seems" like too much though. If you bet 4% it only takes 25 losses to go broke. Even at 5%, that's 1 in 20, it's certainly possible to lose 25.

[d2bets]

d2 do not complicate this

stick to the 1.5 or 2 percent rule

So if I'm betting something at 200-1 or 300-1 I should bet 1.5% or 2% of my bankroll each play?

[d2bets]

how do you know it is 1% guarantee?

It's a hypothetical. Just trying to get an idea.

I mean let's say you have ping pong balls numbered 1 to 100 and one of them is a winner. I give you +20000 to pick the winner. You'd certainly make a wager. I'm just trying to figure out the ideal wager size.

[milwaukee mike]

the problem with questions like this, are that they are way too complicated for stuff like kelly

just a few considerations...

-max wager amount is probably lower than optimal bet amount
-is there a rollover of a bonus? if so you would of course want to go bigger, plenty of value in zeroing out account for new bonus
-will they pay large amounts? depending on the book
-will they lower your limits if it hits?
-will they review your account if it hits, for suspicious activity

[d2bets]

the problem with questions like this, are that they are way too complicated for stuff like kelly

just a few considerations...

-max wager amount is probably lower than optimal bet amount
-is there a rollover of a bonus? if so you would of course want to go bigger, plenty of value in zeroing out account for new bonus
-will they pay large amounts? depending on the book
-will they lower your limits if it hits?
-will they review your account if it hits, for suspicious activity

Fair enough and worthy considerations, but for this exercise I'll assume none of those items are an issue.

[OldBill]

d2 do not complicate this

stick to the 1.5 or 2 percent rule

BINGO thats what wiseguys and sharps do to stay ahead of the books

1.5 to 2% of your bank roll per game if you have $2000 to bet with you only wager $40 per game max 5% $100 per day
i mean if you lose $2000 with max wager $100 per day you best give up gambling on sports

[milwaukee mike]

Fair enough and worthy considerations, but for this exercise I'll assume none of those items are an issue.

then i would also add...

how many times can you hit a situation like this? if it was one-and-done i'm not sure i would even bet it, there's a 99% chance you lose, and that's assuming your 1% estimate is correct... i go back to the old adage "if you flip a fair coin heads 50 times in a row, what are the odds the next flip is heads?"

i would say it's about 100% heads, because the odds that you are lying to me about the fairness of the coin are much greater than the odds of it coming up heads 50 times in a row!

[d2bets]

then i would also add...

how many times can you hit a situation like this? if it was one-and-done i'm not sure i would even bet it, there's a 99% chance you lose, and that's assuming your 1% estimate is correct... i go back to the old adage "if you flip a fair coin heads 50 times in a row, what are the odds the next flip is heads?"

i would say it's about 100% heads, because the odds that you are lying to me about the fairness of the coin are much greater than the odds of it coming up heads 50 times in a row!

Haha. Another great point. Personally, I would still bet as a one and done, because value is value.

But yeah, let's say you can bet this fairly frequently. Let's say about 10-12 times per day. 300 to 350 a month. So no, you can't do hundreds per day, but it's not one and done.

[OldBill]

then again i do not care what the odds are it's 50/50 everywhere remember what happened to tyson not preparing for Buster douglass

the odds were so high on Dougalss no local bookie could touch it! As a 42-1 underdog, Douglas earned $1.3 million from the fight while Tyson got $6 million.

[Waterstpub87]

At a 99% loss odds, you would lose 200 in a row ~13.5% of the time. I would not be comfortable with that. Easier to find a lower edges with less total loss.

Thinking on this further, your main risk is going broke due to a terrible streak. You want to lower your variance, as you want the game to last forever so you can steadily extract your edge. At 1/10,000 of your bankroll, it's like 0e to -44 chance of going broke.

[TommieGunshot]

I looked at the Kelley calculator, but I've never done that before and I'm not sure I'm doing it right.
It appears to say 0.505%. But is that right? Sounds like too much since I'd go broke after 200.

Double check your math. Betting 0.505%, it would take a lot more than that to lose everything. It’s over 450 consecutive losses to have a 90% drawdown. There is a 1% chance of that happening. And that is with the most aggressive staking system. With half-Kelly, 200 consecutive losses would still leave you with more than 60% of what you started with; a 13% chance that happens.

[milwaukee mike]

Double check your math. Betting 0.505%, it would take a lot more than that to lose everything. It’s over 450 consecutive losses to have a 90% drawdown. There is a 1% chance of that happening. And that is with the most aggressive staking system. With half-Kelly, 200 consecutive losses would still leave you with more than 60% of what you started with; a 13% chance that happens.

yeah, i think he was assuming the same starting bankroll... but of course as you are losing that many in a row, your bet size is going down under kelly because the bankroll is now lower

[texhooper]

yeah, i think he was assuming the same starting bankroll... but of course as you are losing that many in a row, your bet size is going down under kelly because the bankroll is now lower

But then you realize everything is actually 50/50 because of a boxing match from 35 years ago so then you must ask yourself why reduce at all, the big hit’s right around the corner!

[veriableodds]

Personally don't care for Kelly calculator at all. Keep it simple and just use the % chance of winnings from model #'s. Example 100-1 would be 1. Say if had 2 separate games 60% , and a 40%chance then your number would be .6 on 1, and .4 on the other = 1

[Ian]

I would bet less than what Kelly suggests because it's very easy to overestimate your edge. I would prefer to bet either about 1% of my bankroll or a similar small amount that won't cause me any amount of tilt if/when the bet loses.

Just my opinion...

[Darkside Magick]

Kelly criterion is Flawed for sportsbetting....Using bayes Theorem at +20000 with a 1%edge(belief)..The optimal bet is 0.5 %

[Optional]

Kelly criterion is Flawed for sportsbetting....Using bayes Theorem at +20000 with a 1%edge(belief)..The optimal bet is 0.5 %

that's very close to what Kelly says too.




I think D2bets problem is not thinking .5% is a suitable bet size for ANY bet.

I think the best way to address that issue using Kelly is to limit max odds or edge calculations to a sensible level, like 10% edge is the most you take notice of.

[d2bets]

that's very close to what Kelly says too.




I think D2bets problem is not thinking .5% is a suitable bet size for ANY bet.

I think the best way to address that issue using Kelly is to limit max odds or edge calculations to a sensible level, like 10% edge is the most you take notice of.

No, I'm talking theory. Like, let's say you know for certain your edge. So for example, 100 balls and 1 is the winner. I give you 200-1 odds. The edge is known and exact. Still seems like .5% bankroll is pretty risky. Doesn't seem like it would be that hard to go broke or near-broke.

[Darkside Magick]

that's very close to what Kelly says too.




I think D2bets problem is not thinking .5% is a suitable bet size for ANY bet.

I think the best way to address that issue using Kelly is to limit max odds or edge calculations to a sensible level, like 10% edge is the most you take notice of.

Yeah it is close

[Optional]

No, I'm talking theory. Like, let's say you know for certain your edge. So for example, 100 balls and 1 is the winner. I give you 200-1 odds. The edge is known and exact. Still seems like .5% bankroll is pretty risky. Doesn't seem like it would be that hard to go broke or near-broke.

If the edge is known and true, then you will profit long term by those calculations. No?

So the math of the theory pans out.

I think the real problem is that a 100/1 shot closing at 200/1 is not really a 100% edge in most cases. When we get to odds like that the accuracy is not fine enough.

[Optional]

Full Kelly Criterion say 5.04%

says that for what?


The OPs first post explains in his example Kelly says 0.505%

https://www.sportsbookreview.com/betting-calculators/kelly-calculator/

[Darkside Magick]

If the edge is known and true, then you will profit long term by those calculations. No?

So the math of the theory pans out.

I think the real problem is that a 100/1 shot closing at 200/1 is not really a 100% edge in most cases. When we get to odds like that the accuracy is not fine enough.

The math is precise if edge is known and true. So full Kelly will suffice

[Darkside Magick]

says that for what?


The OPs first post explains in his example Kelly says 0.505%

https://www.sportsbookreview.com/betting-calculators/kelly-calculator/

I type too fast.. You are correct

[TommieGunshot]

No, I'm talking theory. Like, let's say you know for certain your edge. So for example, 100 balls and 1 is the winner. I give you 200-1 odds. The edge is known and exact. Still seems like .5% bankroll is pretty risky. Doesn't seem like it would be that hard to go broke or near-broke.

You’re right, it isn’t “hard” it’s near impossible.

[d2bets]

You’re right, it isn’t “hard” it’s near impossible.

Good to know. So far so good on my angle. I'll stick with kelly betting.

[Gaze73]

I was just about to make a thread about Kelly because I find it stupidly dangerous.

I found this guy I'd like to follow, he has a 11.6% ROI with a very large sample size of almost 5k bets. The win rate is 44% at avg. odds of 2.7/+170.

According to Kelly, with a $1k bankroll you should bet $110.59. He's currently on a run of 2 wins and 11 losses in the past 5 days. If you bet 11% of your BR per bet, it turns out that going 2-11 is not very good for your finances. So I think anything above half Kelly is insane.

[RangeFinder]

I was just about to make a thread about Kelly because I find it stupidly dangerous.

I found this guy I'd like to follow, he has a 11.6% ROI with a very large sample size of almost 5k bets. The win rate is 44% at avg. odds of 2.7/+170.

According to Kelly, with a $1k bankroll you should bet $110.59. He's currently on a run of 2 wins and 11 losses in the past 5 days. If you bet 11% of your BR per bet, it turns out that going 2-11 is not very good for your finances. So I think anything above half Kelly is insane.

Variance is a killer if :

A: You've miscalculated your edge

B. You over play your bankroll because you believe you have that edge.

Happens to a lot of gamblers.

[Gaze73]

Variance is a killer if :

A: You've miscalculated your edge

B. You over play your bankroll because you believe you have that edge.

Happens to a lot of gamblers.

You're saying that hitting 44% of 5000 bets in one year is not good enough to determine your edge? Even if the real edge is 10% instead of 11.6%, going 2-11 at some point is inevitable at those odds, and full kelly will make you feel like a degenerate gambler who just lost over half of the BR in 5 days.

[Darkside Magick]

I was just about to make a thread about Kelly because I find it stupidly dangerous.

I found this guy I'd like to follow, he has a 11.6% ROI with a very large sample size of almost 5k bets. The win rate is 44% at avg. odds of 2.7/+170.

According to Kelly, with a $1k bankroll you should bet $110.59. He's currently on a run of 2 wins and 11 losses in the past 5 days. If you bet 11% of your BR per bet, it turns out that going 2-11 is not very good for your finances. So I think anything above half Kelly is insane.

Kelly criterion is Theory for Sports Betting.. It is not practical because again you cannot know your edge for random(Chaotic) events

Now the sample size can be use a Monte Carlo Simulation of sort where one can infuse Bayes Theorem and get a more optimal bet size

So with 44% win percentage and avg odds of +170 and taking the ROI as and using that as your conditional probability(Bayes Theorem)

The optimal bet size is 4.14%

[texhooper]

Darkside to me if everything is as random and chaotic as you say it is then every now and then we’d have an NBA final score of like 30-27.