Gather 'round people and I will tell you about SD.
Imagine a set of glass tubes standing vertically. Each tube is set vertically next to one another, making a line 20 foot long. Each tube is 4 foot high, open at the top, with an inside diameter of a ping pong ball.
Got the image? Good.
Now let us imagine you were an exactly break-even player, i.e. your average BB/100, averaged over 100,000 hands, is $0.00.
Now take the tube in the dead middle and mark it -$.50 - +$.50 with a grease pencil.
Mark the one to the right of that one as "$.50-$1.50" and the one to the right of that "1.50-2.50" and so on all the way to the right. SImiliarly mark the ones to the left in negative amounts.
OK. Now play 100 hands. Find the BB/100 and put a ping pong ball in the tube which corresponds to the value of the BB/100 of your 100 hands.
Then do it again for another 100 hands, generating a new average for ONLY those 100 hands and put in another ping pong ball.
Repeat 1000 times.
Now you as you look at the tubes the top ball in each tube will define a "bell shaped curve" Remeber that from high school? If not, what you will see is the highest point being in the middle as it is the most probable result (because you actually are a break-even player). The closer to the middle the higher the stack. Your average result is $0BB/100, but there is another component to describing the curve of your results. Is your curve "narrow" or WIDE?
i.e. If your middle value is a 4 ft stack, how far do you have to go left and right before you have a 2 ft stack. you could have a tight cluster where you only have to go a couple of tubes to drop to 2 ft or a dispursed curve where you have to go dozens of tubes over to drop to 2 ft.
This "tightness" of your curve of results is your Standard Deviation of your BB/100 results.
If I recall exactly, the Standard Deviation of your result is how many tubes over (left and right) do you have to go before you have accounted for 63% of all the ping pong balls. So if you have a "tight" curve, your SD might be 3 tubes. If you have a wide curve, you might have a SD of 10 tubes.
So if you have an SD of $10BB/100 then if you play 100 hand sets and play 1000 of them then your result will be with -$10 and +$10 of your average about 63% of the time. The other 27% will fall outside of that range with lesser probabiliy the farther out you go.
Now if that was clear, please clean up those tubes and ping pong balls and get them back to the ITH warehouse.