Help with RoR

kewljason

kewljason

Well-Known Member
#1
#1
I have never fully understood Risk of Ruin, as well as I should. I know enough to know that I want to play with a very small risk of ruin, which is what I try to do by having a minimum of 150 max bets. I have a few questions I am hoping someone can answer that may help me understand better.

In a recent thread, bjcount ran a sim showing a RoR of 2.2 %. My understanding is that if you use that set bet spread, without resizing that the chance of going broke is 2.2%, is that correct? So if you were to resize your wagers at some point, say after losing a third of half your BR, your RoR would be much much less than that, like a fraction of 1%, appraching zero? Or is resizing already calculated into this original 2.2% RoR?

(I think in this specific case the player had a unit of $10 so resizing probably wasn't possible, unless he could find a $5 table, but I am asking in general, not about this specific case)
 
Sonny

Sonny

Well-Known Member
#2
#2
kewljason said:
My understanding is that if you use that set bet spread, without resizing that the chance of going broke is 2.2%, is that correct?
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Right.

kewljason said:
So if you were to resize your wagers at some point, say after losing a third or half your BR, your RoR would be much much less than that, like a fraction of 1%, appraching zero?
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Right again. If the player resizes his bets after a loss then the RoR will be lower. For example, if they start with a 2.2% RoR but agree to cut their bets in half if they lose half of their bankroll then the initial RoR is only 0.33%. BJA has an interesting little trick for calculating this:

http://www.blackjackinfo.com/bb/showthread.php?p=48448

-Sonny-
 
SleightOfHand

SleightOfHand

Well-Known Member
#3
#3
kewljason said:
I have never fully understood Risk of Ruin, as well as I should. I know enough to know that I want to play with a very small risk of ruin, which is what I try to do by having a minimum of 150 max bets. I have a few questions I am hoping someone can answer that may help me understand better.

In a recent thread, bjcount ran a sim showing a RoR of 2.2 %. My understanding is that if you use that set bet spread, without resizing that the chance of going broke is 2.2%, is that correct? So if you were to resize your wagers at some point, say after losing a third of half your BR, your RoR would be much much less than that, like a fraction of 1%, appraching zero? Or is resizing already calculated into this original 2.2% RoR?

(I think in this specific case the player had a unit of $10 so resizing probably wasn't possible, unless he could find a $5 table, but I am asking in general, not about this specific case)
Click to expand...
The "RoR" that is usually quoted is the probability of going bust before doubling your BR if you do not resize. There is another equation to find a lifetime RoR as well (I believe on BJ21). However, when resizing your bet spreads, you have a RoR of 0%, assuming no table limits and betting fractional $'s.
 
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Deathclutch

Deathclutch

Well-Known Member
#4
#4
Sonny said:
Right.



Right again. If the player resizes his bets after a loss then the RoR will be lower. For example, if they start with a 2.2% RoR but agree to cut their bets in half if they lose half of their bankroll then the initial RoR is only 0.33%. BJA has an interesting little trick for calculating this:

http://www.blackjackinfo.com/bb/showthread.php?p=48448

-Sonny-
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Maybe I'm not reading this correctly. So if a person has a 2.2% ROR and then loses three quarters of the bankroll, but continues to play exactly the same the initial ROR is still the same? But that differs from the current ROR, correct?
 
B

bjcount

Well-Known Member
#5
#5
kewljason said:
In a recent thread, bjcount ran a sim showing a RoR of 2.2 %. My understanding is that if you use that set bet spread, without resizing that the chance of going broke is 2.2%, is that correct? So if you were to resize your wagers at some point, say after losing a third of half your BR, your RoR would be much much less than that, like a fraction of 1%, appraching zero? Or is resizing already calculated into this original 2.2% RoR?

(I think in this specific case the player had a unit of $10 so resizing probably wasn't possible, unless he could find a $5 table, but I am asking in general, not about this specific case)
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Kewl J,

per cvcx: Risk of Ruin. That is, the risk that you will lose your entire bankroll.

Lets say you lost 50% of your bankroll maintaining the same min bet and same bet spead. As your BR is diminishing from loses the RoR is increasing. So in the example sims you refer to acbjpro has an 18k BR. If he lost 1/2 of his BR and does not resize his min bet he will be playing with a 10.5% RoR with his 9k BR thats left.

CVCX does not automatically take into consideration any resizing of bets to calculate the RoR, the RoR stated in the sim is based on the values you put in.

BJC
 
SleightOfHand

SleightOfHand

Well-Known Member
#6
#6
Sonny said:
Right.



Right again. If the player resizes his bets after a loss then the RoR will be lower. For example, if they start with a 2.2% RoR but agree to cut their bets in half if they lose half of their bankroll then the initial RoR is only 0.33%. BJA has an interesting little trick for calculating this:

http://www.blackjackinfo.com/bb/showthread.php?p=48448

-Sonny-
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Ooh handy equation for calculating your adjusted RoR. Is there a way to calculate a different adjusted RoR? Say re-evaluating your spread after losing 20% of your BR?
 
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bjcount

Well-Known Member
#7
#7
Sonny said:
If the player resizes his bets after a loss then the RoR will be lower. For example, if they start with a 2.2% RoR but agree to cut their bets in half if they lose half of their bankroll then the initial RoR is only 0.33%. BJA has an interesting little trick for calculating this:

http://www.blackjackinfo.com/bb/showthread.php?p=48448

-Sonny-
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Sonny,

By your explanation, your going pre-loss, your RoR of 0.33% is based on the original BR, not your current diminished BR.

If he resizes after a lose the ROR would be lower based on the current BR, not the original.

But now its too late, you are at a lower BR. If you resize it has to be determined based on your current BR or you would be over betting your roll.

BJC
 
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B

bjcount

Well-Known Member
#8
#8
kewljason said:
I have never fully understood Risk of Ruin, as well as I should. I know enough to know that I want to play with a very small risk of ruin, which is what I try to do by having a minimum of 150 max bets. I have a few questions I am hoping someone can answer that may help me understand better.
Click to expand...
Lets say your u = $10 with a 1-12 spread and your roll is 150 max bets.
Thats exactly the example acbjpro gave using an $18k BR.

So if it was 2.2% RoR to begin with and never resized, if you lose 1/2 your roll, the RoR for a 9k BR using the same min bet and spread has become 10.5%.

Also consider he was always WO at exactly -2 with a single hand spread. The 2 hand spread cuts the ror in half.

BJC
 
B

bjcount

Well-Known Member
#9
#9
SleightOfHand said:
However, when resizing your bet spreads, you have a RoR of 0%, assuming no table limits and betting fractional $'s.
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SOH

This is based on your original starting BR.
If you lose half of your BR and resize, then the RoR should be based on your new BR. Obviously if you resize your minimum bet lower and use your original starting BR the RoR number will be lower, like 0.33%, but you no longer have that same BR, so how can you consider the original BR in the equation.

BJC

Edit: maybe I'm not understanding the concept here but isn't the reason to resize as your BR diminishes is to maintain the same RoR with in your risk tolerance? Based on some of the points made your going from 2.2% to 0.33% as your losing money and lowering your bet. It sounds like it will take 2 or 3 life times to recover your initial 50% loss
 
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Sonny

Sonny

Well-Known Member
#10
#10
bjcount said:
Edit: maybe I'm not understanding the concept here but isn't the reason to resize as your BR diminishes is to maintain the same RoR with in your risk tolerance?
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Right. It sounds like you understand the concept fine, it's just that we are all talking about different things. Maybe it will help if we consolidate everything.

If you lose a portion of your bankroll and then cut your bets in that proportion then you are back to your original RoR. (As you said)

If you plan to adjust your bets if your bankroll shrinks (but before it shrinks) then your initial RoR is lower. (As I said)

The more often you resize your bets, the closer you get to a theoritical 0% RoR. (As SOH said)

I think that just about covers it. :)

-Sonny-
 
A

assume_R

Well-Known Member
#11
#11
Sonny said:
Right. It sounds like you understand the concept fine, it's just that we are all talking about different things. Maybe it will help if we consolidate everything.

If you lose a portion of your bankroll and then cut your bets in that proportion then you are back to your original RoR. (As you said)

If you plan to adjust your bets if your bankroll shrinks (but before it shrinks) then your initial RoR is lower. (As I said)

The more often you resize your bets, the closer you get to a theoritical 0% RoR. (As SOH said)

I think that just about covers it. :)

-Sonny-
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That indeed just about covers it. The only additional thing to consider is if the lowest "Table Minimum Bet" in the US is a certain value, say $5, there will indeed be a minimum practical RoR that can be obtained and it will be larger than 0%. To calculate it you would just have to figure out the probability of having to resize your unit size to $5 (i.e. the probability your bankroll would be reduced to, say, $4,000 or so), and multiply that by your original bankroll's RoR.
 
kewljason

kewljason

Well-Known Member
#12
#12
Sonny said:
Right. It sounds like you understand the concept fine, it's just that we are all talking about different things. Maybe it will help if we consolidate everything.

If you lose a portion of your bankroll and then cut your bets in that proportion then you are back to your original RoR. (As you said)

If you plan to adjust your bets if your bankroll shrinks (but before it shrinks) then your initial RoR is lower. (As I said)

The more often you resize your bets, the closer you get to a theoritical 0% RoR. (As SOH said)

I think that just about covers it. :)

-Sonny-
Click to expand...
Ok gang, I appreciate the quick responses. Sonny's explanation was more or less what I wanted to hear. When I run my numbers thru CVCX I get a RoR between between 2 and 3% (BR 55K, max bet 400) which is higher than I would like, but as long as I am willing to resize smaller should I lose a significant portion of BR (which I am willing, but wouldn't be happy about) I am in reality playing at a lower risk. The chances of me going bust are now at a very low level, that I am more comfortable with. Is this correct thinking?
 
daddybo

daddybo

Well-Known Member
#13
#13
kewljason said:
Ok gang, I appreciate the quick responses. Sonny's explanation was more or less what I wanted to hear. When I run my numbers thru CVCX I get a RoR between between 2 and 3% (BR 55K, max bet 400) which is higher than I would like, but as long as I am willing to resize smaller should I lose a significant portion of BR (which I am willing, but wouldn't be happy about) I am in reality playing at a lower risk. The chances of me going bust are now at a very low level, that I am more comfortable with. Is this correct thinking?
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I think so. :)
 
B

bjcount

Well-Known Member
#14
#14
kewljason said:
Ok gang, I appreciate the quick responses. Sonny's explanation was more or less what I wanted to hear. When I run my numbers thru CVCX I get a RoR between between 2 and 3% (BR 55K, max bet 400) which is higher than I would like, but as long as I am willing to resize smaller should I lose a significant portion of BR (which I am willing, but wouldn't be happy about) I am in reality playing at a lower risk. The chances of me going bust are now at a very low level, that I am more comfortable with. Is this correct thinking?
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I'm glad we are all on the same page now.

KewlJ, just a quick thought:

I'm looking at the sim I ran for acbjpro yesterday and approximated your method of play (by what I can only surmise) by changing some of the numbers.

Have you looked at playing 2 hands at TC+1 with the same spread and max? My sims show the RoR drops by more then half. What are your thoughts?

BJC
 
kewljason

kewljason

Well-Known Member
#15
#15
bjcount said:
I'm glad we are all on the same page now.

KewlJ, just a quick thought:

I'm looking at the sim I ran for acbjpro yesterday and approximated your method of play (by what I can only surmise) by changing some of the numbers.

Have you looked at playing 2 hands at TC+1 with the same spread and max? My sims show the RoR drops by more then half. What are your thoughts?

BJC
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It was that sim you ran yesterday which got me thinking about the whole situation, as those numbers weren't that different than mine. Different unit size, but proportionally similar. I did take note of your second sim, where spreading to 2 hands reduced the RoR by 50% (2.2 to 1.1%) Occassionally I do spread to two hands, however I have found and been advised by a couple of players that also play at this level, that I have high regard for, that spreading to 2 hands during plus counts is perhaps the single most tell of a counter. More than how you play insurance. More than perhaps the spread itself. For that reason I don't often spread to 2 hands.
 
B

bjcount

Well-Known Member
#16
#16
Agreed, most obvious tell.

If your WI@+1 then playing 2 hands on entry, I would have to presume shouldn't be an issue. It's once your down to 1 hand at 0 that going back out to 2 should be a no-no.

IMO of course.

BJC

Edit: How ever you play it, keep up the good work!

Edit 2: RoR is only a tiny piece of the improvement, look at the SCORE, N0, and CE too
 
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