# Deviation Basic

#### lucky21

##### Dormant account
Hi Folks
I am trying to get my head around standard deviation, can anybody explain it simply in a win loss example i.e. for 1000 hands played standard deviation may mean i lose 50 hands more than expected or am up 50 hands more than expected. or something like that.

playing on position, 6decks no surrender, double after split,

cheers
Fitz

Hope you are all watching the bathurst car races!

#### lucky21

##### Dormant account
checked out calc

Thanks winbig
I checked out the calculator and it gives me a standard deviation of 1.15 per hand, so 1000hands would be 1150 does this mean that i could lose or win 150 hands outside expectations per thousand?

#### winbig

##### Keep winning this amount.
Thanks winbig
I checked out the calculator and it gives me a standard deviation of 1.15 per hand, so 1000hands would be 1150 does this mean that i could lose or win 150 hands outside expectations per thousand?
It should say on there.....I'm horrible at stats

But for something to be amiss, you would have to be over 3SD in either direction....

#### aka23

##### Dormant account
Thanks winbig
I checked out the calculator and it gives me a standard deviation of 1.15 per hand, so 1000hands would be 1150 does this mean that i could lose or win 150 hands outside expectations per thousand?
It means that after 1000 hands with a 1-unit bet size, you have a 68% chance of being within mean +/- 1.15*SQRT(1000) units, a 95% chance of being within mean +/- 2*1.15*SQRT(1000) units, and a 99.7% chance of being within mean +/- 3*1.15*SQRT(1000) units. It may be more intuitive to use SD to compare variance with other games. A coin flip has a SD of 1. So after 1000 BJ hands, your expected range of return is 1.15x what it would be with 1000 coin flips.

In addition to the house edge calc linked above, there are other calcs on my site that do variations of the above calculations, such as the return & variance calc and "Are my results fair?" calc.

#### lucky21

##### Dormant account
more basic lol

Thanks AKA
I have seen those figures of sd and such but still dont really make sense of it, sorry for sounding dumb but is there a figure of wins or losses per thousand hands that should really allert me there is a problem, i have such strange losses with a 14 loss, few 9 losses, 10losses in a row in one session as well as the game seeming to know when i bet big, A common complaint i know, but i am trying to understand it to attribute it to variance as the casino manager tells me that what it is.

I have looked at wizard of odds charts and can make some sense of them.

The problem i see with strange play is no matter how strange there is still a possiblity of that strange play happening so there lies there fair play dilemma

#### lucky21

##### Dormant account
thinkin out loud

Just thinkin out loud, but in this variance or deviation thing, is it worthwhile counting wins and losses when playing and when the deviation is in the maximum losses range I could then hedge a few bets in anticipation of the deviation swinging the other way- towards the good side.

Off coarse all this would have been done before by someone, just trying to work out if it is of any benefit, I have two counters in my hand when i play so i know wins and losses, I just dont know how to work out a good time when the bad swing should change.

Suppose if it was easy blackjack would be banned.

#### aka23

##### Dormant account
Just thinkin out loud, but in this variance or deviation thing, is it worthwhile counting wins and losses when playing and when the deviation is in the maximum losses range I could then hedge a few bets in anticipation of the deviation swinging the other way- towards the good side.
No, it is not worthwhile. In a fair game, future results are independent of past results (ignoring card counting type issues). You are just as likely to have a win, if the past 10 hands were wins, as if the past 10 hands were losses.

#### lucky21

##### Dormant account
example

Here is an example of what i mean

in the session i am playing right now i have had 822lost hands and 717winning hands, i dont count pushes, is this within variation/deviation expectations?

Cheers
Lucky

#### DiamondGeezer

##### Dormant account
PABaccred
PABnoaccred
PABnononaccred2
The first thing is you need to count the pushes as they contribute to the total hand count.

I am looking at the Woo probability of loss table. You don't know the push count but it looks like you played approx 1750 hands. According to the table there is about a 1% chance of this result.

Looks like a plain old bad result to me. But if it was to be a real monster you could expect to lose another 60 units or more in the session. So I would say this was a normal if bad result.

Hope you have better luck next time.