Standard Deviation - clear it up for me

[SomethingClever]

My standard deviation per 100 hands is 17.1

I'm trying to figure out if this is good, bad, or average. I think I've been told it's on the high side, but nobody ever really explained it.

I play limit HE from .5/1 to 2/4.

[EliteNinja]

Standard Deviation can be used as an indicator of your aggressiveness. The higher it is, the more aggro you are. I does not tell you too much about your tightness or looseness. Also, it totally depends on the games that you play, if you always play with maniacs, your standard deviation would most likely go up. Loose-passives => SD goes down.

Ofcourse, being only a single type of data on your game, it could not tell you as much about how you play as Poker Tracker could.

Another use for Standard Deviation is to keep your bankroll in check by calculating your 95% Confidence Interval and your Risk of Ruin. Since I have to sleep now, I will not "engage stats mode". I'll let you find out how to calculate these statistics.

This is what I have learned from these forums from lurking. And since I am a n00b, someone please correct my thinking.

[uuDevil]

[ QUOTE ]
My standard deviation per 100 hands is 17.1

I'm trying to figure out if this is good, bad, or average. I think I've been told it's on the high side, but nobody ever really explained it.

I play limit HE from .5/1 to 2/4.

[/ QUOTE ]

This is kind of hard to answer. If you want to know if it is high or low, you'd have to compare it to data from other players, but this isn't readily available as far as I know. Just based on numbers I've seen, this may be on the high side of typical, but not out of line. At $.5/1, mine is about 14BB/100. It might be a good idea to do a poll in the micro forum if you want to see how you compare to some of your peers.

If you have a good win rate and your bankroll can handle this amount of variance, I don't see any reason for concern. If you haven't calculated your bankroll requirements based on SD and WR, you should. You can find many posts on this topic by doing a search.

[BigBaitsim (milo)]

I play mostly 2/4 & 3/6 at Party. My SD is 18.5 BB/100. I play fairly aggressively, but a bit looser than many at 2+2 with a V$IP of 19.32.

[tpir90036]

It's only bad if your win rate doesn't out pace it after a great number of hands. Which should always happen if you are a winning player... it just might take longer to get there and you might run the risk of going broke if your bankroll is not big enough.

For example:
Let's say you played 10000 hands or a hundered, 100 hand sessions. Find out your expected win rate over this period and then multiply your standard deviation by the square root if this number. If you do not understand the square root part I recommend going through the archives and looking for a mathematical explanation of SD and the units involved. Anyway...

For a win rate of 3BB/100:
3 * 100 = 300
17.1 * 10 = 170

If your win rate was only 1BB/100:
1 * 100 = 100
17.1 * 10 = 170

Oops! Our SD is bigger than out win rate... so in the short term we could be in trouble. This does not mean that we can not be a winning player... only that it will take longer to have confidence in our results since we will have bigger swings.

So now let's play 10,000 hundred hand sessions. A lot of hands!
1 * 10,000 = 10,000
17.1 * 100 = 1,710

So over a great number of hands we shold be ahead if we are a winning player... but we could go through big losing swings if our win rate is low and our SD is high. Better have a bank roll that can handle it.

-tpir