Standard Deviation

[reecelights]

Sorry about this post, I did a search to try to read up on Standard Deviation, but...

As a relative newbie to these forums, I see a lot of discussion about SD and Variance. I also now have the 2+2 SnG spreadsheet (thanks, Jurollo, Aleo Magus, et al.).

I've never read about SD before and don't understand what this statistic is indicative of, and what a desirable SD is for SnGs. Most of the other discussion of SD on the site is for limit, ring games.

Any definitions would be appreciated by myself, and, I imagine, a number of others who don't understand this.

Never afraid to ask the "dumb" question,
Chuck

[mackthefork]

Well I understand what it is, how its measured, and that it has a relevance to variance, but i have no idea which stat they measure the SD of, or why they can use it to calculate confidence figures. I always say, if you need a calculator to do a calculation, its a calculation can do without (maybe). [img]/images/graemlins/grin.gif[/img]

Regards Mack

PS Many true word spoken in jest.

[reecelights]

I've been pretty confident about my confidence the last two weeks, and I'm frequently deviant, and would never want to do a square root in my head during play or have it effect my play.

Still wondering what the hell this all means...

[Irieguy]

Standard deviation is a measure of variance. Specifically, it is the square root of the variance from the mean. It's a square root so that the number will always be non-zero, and it will be expressed in the same unit as all the other data.

It is a measure of how close a typical result is to the mean result in a large sample. If your SD is big, that means that most results are not very close to your mean result. If your SD is very small, that means that most results fall very close to your mean.

As a Sit N Go player, your mean result per tournament will be some fraction of a buy-in (either + or - depending on whether you play winning or losing poker.) But your actual result will be a multiple of the buy-in (-1, +1, +2, +4 at Party, ignoring vig). Because of the payout and buy-in structure, your individual results will all be far from the mean. So, your variance will be relatively large as will your Standard Deviation. Your specific SD will depend upon the proportion of different finishes you have. 1st place affects your variance more than any other result.

My opinion is that the structure of most forms of poker affects SD more than an individual's performance. So, regardless of whether you are a winner or a loser, your SD is probably going to be pretty similar to other players who play the same game at the same limit.

Hope this answers your question.

Irieguy