Standard Deviation....of Blackjack?

[LondonBroil]

Non-poker related post.

I decided to post this after returning from a trip to Vegas where I had 2 killer blackjack sessions. I don't play too often but the last 3 times I've gone to A.C. I've come out a descent winner (30~40x my bet) with maybe 3-4 hours of playing. I know the game is supposedly -EV in the long run, but I've memorized the standard strategy and use a basic counting strategy (I've always been extremely proficient in basic mathematics being able to add, subtract, multiply, and divide numbers very quickly) so maybe I can beat it?

Basically, whenever my g/f and I go to A.C., she ALWAYS loses, mostly because she doesn't always do what your "supposed" to do. She likes staying on 16, she doesn't always double on 11, etc.

If I gave her the basic card sheet, and she memorized it, it cuts the casino advantage to around 2.6% (I think). Is there a way to figure out a Standard Deviation per x number of hands played, say 100 hands?

[Cyrus]

"Is there a way to figure out a Standard Deviation per x number of hands played, say 100 hands?"

Your Standad Deviation per x number of hands will be your SD per hand multiplied by the square root of x. If your SD per hand is $5 and x=100, then the SD for those 100 hands is $50.

[LondonBroil]

Ok then, is there a way to figure out your SD per hand if the house advantage is say.....2.5% ?

[Cyrus]

"Is there a way to figure out your SD per hand if the house advantage is say 2.5% ?"

The quick and dirty approach is to accept your hand's EV multiplied by 1.1 (in order to account for the naturals, etc) as your hand's SD. If your EV per hand is +$5, than (1.1)*($5)= $5.5 is your SD/hand. (Those who insist on exactitude of terminology will protest that the term "SD per hand" is not correct, but this is unimportant for ..the issue at hand. Forgive the pun -- and carry on.)

However, this would underestimate, and arguably very seriously, your true SD! And calculating the true SD in Blackjack is no trifling matter, if I may say so on the basis of my limited knowledge of the game.

For an in-depth, though not too tough to comprehend, text about variance in Blackjack, I cannot possibly recommend any other book but Don Schlesinger's classic "Blackjack Attack (2nd edition)". It is available in most BJ websites, which you are kindly asked to support with your purchase, choosing one of them as your shop instead of an amazon.com.

--Cyrus

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