Definition for variance and standard deviation

[Ludanto]

What are the definitions for variance and for standard deviation (which is used in Poker Tracker)? Are these two things something specific or is it a matter of opinion? If there are different definitions I would also be interested. It seems to me as if this would allow somebody to express a relation between luck and time in numbers.

[kazana]

Those two things are very specific, and strongly related.
Namely, Variance = (Standard Deviation)²

For more information start here:
Wikipedia on Variance
Wikipedia on Standard Deviation

[Ludanto]

Thank you very much for the links kazana. Both of the wikipedia articles seem to exactly express what I wanted to know. I think that I will need some time to fully comprehend those contents but I am happy that I now have a mathematical definition for variance and standard deviation.