Just got rocked at the $50 table - question on standard deviation

[bjarg]

That's 10 top wagers. I don't know if that qualifies as "getting rocked".

Just got back from dropping 45k.
I think I got rocked.

[ZeeBabar]

Aaaah! $45 k in one session. Worst one session loss for me in my year+ has only been $2200. Do you carry that big a trip BR or get credit or what? I keep $2-3k for a session BR and the most has been $10k for a longer 3-5 day trip.

[Bigdaddy]

I know this is your local casino and this may not be possible, but if you could find say a $25 table that wasn't watched as closely, and you could spread to 6, you'd have the same win rate and your SD would be 2/3 of your present game. You'd also drop N0 to 11,000 from 21,000.

Good observation - yes, this place does have a $25 DD table, but it's H17 and always 5-6 spots taken + the dealer (so maybe 4 hands per shoe). I realize that I could get the same results at this H17 table by going 1 or 2 higher on my spread and it would also reduce my SD, but the slow speed of that game drives me nuts.

[KJ]

Just got back from dropping 45k.
I think I got rocked.

Well, that depends. If your max bet was $5000, I'd have to say no, just a routine swing with a large bet. I think getting 'rocked' is something a little more outside of normal handful of max bet losses. That was my point with the OP.

But in your case, I am sure you know whether you got 'rocked' or not and if you say you did, I am sure you did.

Either way, I guess it is better to get 'rocked' than to get 'stoned' (using the punishment definition of stoned).

[ZenMaster_Flash]

Using round numbers (depends on your ramp), I make the per-hand win rate about $.60-$.65 and the per-hand s.d. about $100. If you played 150 hands, your e.v. was to win about $95, and your s.d. was about $1,225. To lose $1,500, when you were supposed to win $95 represents a negative s.d. of 1595/1225 = 1.30. This happens with probability 9.7%. So, clearly, not terribly unusual.

Don

Peeps here need to re-read this 'perfect' post by Don.

9.7% is taken from a table of "Z-Scores" It is NOT complex. It is really Statistics 101, as so to speak.

I imagine that most of our brethren are unaware that such a profoundly valuable asset is easily found.

[Shadowless]

Thanks, and by the way - I'm going back tomorrow to get it back... maybe spread 1-4 next time....

OP,

Be careful with the "I'm going back tomorrow to get it back" mentality.
Eventually you WILL get money back (and more), but it doesn't have to be all at once, nor does it have to be immediately.

I've fallen victim to using a larger spread and even increasing my base unit, and thus my RoR, just to get money back after a bad run.
I was fortunate to get money back, but what was the cost? Not being welcome to play blackjack at that particular casino anymore.

Remember, even you said you don't sh... where you eat.

[ZenMaster_Flash]

I am not "reading too much into this" - when players say what you have said -
it signals a strong implication that you harbor a dangerous mentality, to wit …
a session result or a daily result somehow has ANY significance at all and you
Are thinking like a "degenerate" who is "steaming" and "chasing" losses.
The CORRECT path for you is to become more conservative and adjust your
level of action to account for an increased ROR due to a degraded bankroll.

[Bigdaddy]

I am not "reading too much into this" - when players say what you have said -
it signals a strong implication that you harbor a dangerous mentality, to wit …
a session result or a daily result somehow has ANY significance at all and you
Are thinking like a "degenerate" who is "steaming" and "chasing" losses.
The CORRECT path for you is to become more conservative and adjust your
level of action to account for an increased ROR due to a degraded bankroll.

Thanks ZenMaster and Shadowless - message received and agreed.
I was joking around a bit. I'm not a chaser. Actually the $1,500 loss is quite insignificant in comparison to my resources. Blackjack is a game for me and I like to play with an advantage for the fun and challenge and I like to be good at what I do. So I really appreciate this forum and the advice of the seasoned experts - helps to keep my head straight...

[Nikky_Flash]

let us know how the next sessions play out... good "luck" to you

[SiMi]

Hey, BD

If you want to calculate this type of stuff for yourself, here's a link to a free e book all about N0 that will help you determine the probability of losing $x after N rounds of play under given conditions if you know your SD and your EV. (I used CVCX to get those figures.)

http://www.blackjackstartup.com/N028.htm

As Don said, your bet ramp was not specified but, assuming an optimal ramp per Norm's software, you had a SD of 1.31 and an average bet of $76.11 per round. Your EV was 0.783%. So, you can calculate your Accumulated SD as the square root of the 150 rounds you played times the SD as follows:

sqrt(150) * 1.31 = 16.04 Accumulated SD

Then, multiply the ASD times your Average bet of $76.11 to get your ASD in terms of your average bet:

16.04 * 76.11 = 1220.80

Then, calculate your EV as Total Bet times EV:

$76.11 per round * 150 rounds = $11,416.50 times 0.783% = $89.31 (this was your expected win after 150 rounds)

Then, calculate your Actual Deviation which is your Actual Result - EV:

-$1500 - $90 = -$1590

And divide that by your Accumulated Deviation to get your ACTUAL Standard Deviation:

-$1590 / 1220.80 = -1.30

Finally, look in a "left of Z Table" to find the probability of experiencing a NEGATIVE 1.3 SD event. The ebook link I sent you has a Z Table and it shows the proportion is 0.0968 for -1.30.

In other words, the probability was, as Don said, 9.68%. These numbers give you another view of the game you're playing and going through the calculations help you see if it's worth it.

I hope this helps!
SiMi

[Bigdaddy]

Hey, BD

If you want to calculate this type of stuff for yourself, here's a link to a free e book all about N0 that will help you determine the probability of losing $x after N rounds of play under given conditions if you know your SD and your EV. (I used CVCX to get those figures.)

http://www.blackjackstartup.com/N028.htm

As Don said, your bet ramp was not specified but, assuming an optimal ramp per Norm's software, you had a SD of 1.31 and an average bet of $76.11 per round. Your EV was 0.783%. So, you can calculate your Accumulated SD as the square root of the 150 rounds you played times the SD as follows:

sqrt(150) * 1.31 = 16.04 Accumulated SD

Then, multiply the ASD times your Average bet of $76.11 to get your ASD in terms of your average bet:

16.04 * 76.11 = 1220.80

Then, calculate your EV as Total Bet times EV:

$76.11 per round * 150 rounds = $11,416.50 times 0.783% = $89.31 (this was your expected win after 150 rounds)

Then, calculate your Actual Deviation which is your Actual Result - EV:

-$1500 - $90 = -$1590

And divide that by your Accumulated Deviation to get your ACTUAL Standard Deviation:

-$1590 / 1220.80 = -1.30

Finally, look in a "left of Z Table" to find the probability of experiencing a NEGATIVE 1.3 SD event. The ebook link I sent you has a Z Table and it shows the proportion is 0.0968 for -1.30.

In other words, the probability was, as Don said, 9.68%. These numbers give you another view of the game you're playing and going through the calculations help you see if it's worth it.

I hope this helps!
SiMi

Thanks SiMi. I got it - AD/ASD = z. Then look up the z score for the probability. My college stats professor would be proud to know that one of his beer-guzzling students is looking up z scores some thirty years later. Just hope next time I'll be looking one up on the positive side of the table....