Hey Gospy,
A quick explanation of how it works:
There are a couple of assumptions you have to make:
a) Game conditions, the players mood/skill level/tilt level and hence their expected winrate never change.
b) Your results in a 100 hand block are distributed normally around your true winrate.
These assumptions clearly make the simulation naive one since in reality a) will never be satisfied. (I'm not sure about b).
So given these two assumptions the simulation works by picking a series of random values distributed normally around your winrate (with the input standard deviation), and then the chart is created by plotting the cumulative sum of those values vs the length of the series (i.e. the number of hands/100).
For example If we were to do a 500 hand sample with a winrate of 10bb/100 then you might get results that look like this
Trial | Win | Cumulative |
1 | 30 | 30 |
2 | 50 | 80 |
3 | -120 | -40 |
4 | 70 | 30 |
5 | -20 | 10 |
Let me know if that doesn't make sense.
edit: to answer your question, each jump is considered independent of previous ones.
edit 2: I am no statistics expert