Risk of ruin questions

kebo15706

kebo15706

Member
Hello everyone. I'm new to this site. I've been practicing for about 4 months (using the Hi-lo system). I have not played in a casino yet but that is because I don't have a bankroll yet. When tax season comes I plan on having a bank roll of $5000 dollars. My plan is to have a 25$ dollar unit with a max bet of $100 (1-4 spread). I used 2 online risk of ruin calculators and they both said my risk of ruin was 3.66%. This looks really good looking at it, but is this really accurate? Is my risk of ruin really 3%? Does that mean I have a 97% chance of doubling up?? I have the other aspects of the game figured out but this is kind of a murky area for me. Any help would be great. Thanks.
 
Sonny

Sonny

Well-Known Member
kebo15706 said:
When tax season comes I plan on having a bank roll of $5000 dollars. My plan is to have a 25$ dollar unit with a max bet of $100 (1-4 spread). I used 2 online risk of ruin calculators and they both said my risk of ruin was 3.66%.
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With a 1-4 spread and only a 200 unit bankroll I'm pretty sure your risk of ruin is MUCH higher than 3.66%. I would guess it to be closer to 35% (with a 65% chance of not busting out), but I don't know what kind of games you are playing or what your strategy is.

-Sonny-
 
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PierceNation

Well-Known Member
Playing a 'decent' game with a 10k bankroll, betting 10-100 is roughly 5% RoR. I would agree with everyone else that a 25 unit is way way too high and strongly recommend you SIM the games you will be playing but with a 5K br I would think 5-50 dollar spread would work quite well.
Yes, it would mean a 97% chance of doubling up, but theoretically that could take quite some time, years even.
If I were you id reasess your bets everytime your br fluctuates 20% up or down, and not worry to much about doubling up.
 
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DonFinuchi

Active Member
While we are on the topic (read: sorry for hijack)

I'm having some trouble understanding how one can declare a static RoR for applying a given strategy to a given game without discussing volume. I can understand how you can calculate a RoR for playing a given strategy and game for a predefinded number of rounds, or say until one either doubles or busts their roll.

Would it not be correct to say that, in theory, if we play for an infinate number of rounds, we would all have a RoR of 100% (murphys law)?
 
blackjack avenger

blackjack avenger

Well-Known Member
infinite, not that far

DonFinuchi said:
I'm having some trouble understanding how one can declare a static RoR for applying a given strategy to a given game without discussing volume. I can understand how you can calculate a RoR for playing a given strategy and game for a predefinded number of rounds, or say until one either doubles or busts their roll.

Would it not be correct to say that, in theory, if we play for an infinate number of rounds, we would all have a RoR of 100% (murphys law)?
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The short run bank is similar to the infinite bank because the variance is high. This is why session banks are so large.

The ror is just that, 5% ror means a 95% chance of not going broke.

In theory a Kelly resizing bank has 0% ror.
In reality 1/4 to 1/8 Kelly resizing bank should have 0% ror
 
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QFIT

QFIT

Well-Known Member
The calculator you are pointing to uses the "simple risk of ruin" formula, the simplest of several RoR formulae that can be used in gambling. But, it is still reasonably accurate, assuming the correct input. As others have said, the result suggests the input may not be correct.
 
QFIT

QFIT

Well-Known Member
PierceNation said:
Million Dollar Blackjack has a fantastic section on risk of ruin

Pierce
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Blackjack Attack's section on RoR is vastly more comprehensive.
 
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cgy606

Member
kebo15706 said:
Win rate $25
Standard deviation $275
bankroll $5000
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Hi,

The problem with your numbers is the SD is very low. The Win rate is about right (1 unit / 100 is roughly what you would get on a DD game 1.1/2 pen). Some people have told you that for spreading 1-4 is only good enough for single deck. A 1-4 spread is also "good enough" for a double deck game if the rules and pen are good (Still quite though conservative). For example, there is a DD game close to me that is 2D S17+DAS+RSA that usually cuts off 1/2 deck or less! Assuming Hi-Low plus I18, you are looking at µ=1.76/100 hands and σ=22.15/100 hands with a play all approach (Sorry, DD games tend to be No Mid Shoe entry and they will get suspicious if you sit out too many negative counts). A 5K bankroll would give you an RoR of 23.74%. A better approach would be to save up more money or play with a smaller unit size if you can find such good conditions as I mentioned (which unfortunately you won't, $10 DD games will most likely be H17 with no RSA and not as well cut).

To get an RoR of 3% you need 488 units which is $12,200 for $25 units. I hope this is helpful
 
kebo15706

kebo15706

Member
cgy606 said:
Hi,

The problem with your numbers is the SD is very low. The Win rate is about right (1 unit / 100 is roughly what you would get on a DD game 1.1/2 pen). Some people have told you that for spreading 1-4 is only good enough for single deck. A 1-4 spread is also "good enough" for a double deck game if the rules and pen are good (Still quite though conservative). For example, there is a DD game close to me that is 2D S17+DAS+RSA that usually cuts off 1/2 deck or less! Assuming Hi-Low plus I18, you are looking at µ=1.76/100 hands and σ=22.15/100 hands with a play all approach (Sorry, DD games tend to be No Mid Shoe entry and they will get suspicious if you sit out too many negative counts). A 5K bankroll would give you an RoR of 23.74%. A better approach would be to save up more money or play with a smaller unit size if you can find such good conditions as I mentioned (which unfortunately you won't, $10 DD games will most likely be H17 with no RSA and not as well cut).

To get an RoR of 3% you need 488 units which is $12,200 for $25 units. I hope this is helpful
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I was using Semyon Duckach's Dvd black jack science for the standard deviation calculations.
 
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Nynefingers

Well-Known Member
kebo15706 said:
I was using Semyon Duckach's Dvd black jack science for the standard deviation calculations.
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$275 is roughly the standard deviation for 100 hands of flat-betting $25. You're spreading your bets, so that number will be higher. I didn't look back at the specifics of your strategy and your game, but somebody should be able to run a sim for you pretty easily.
 
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