SQN calculation not using expectancy?

Hi,

It's good to see the stats include SQN. According to https://evilspeculator.com/tools-section/concepts/:

SQN = root(n) * expectancy / stdev(R)

but I suspect it's not correctly calculated:

https://github.com/kernc/backtesting.py/blob/77f4c46b82169c2689e1c4ad5994765556179eb2/backtesting/_stats.py#L139

as it's not using the result of expectancy:

https://github.com/kernc/backtesting.py/blob/77f4c46b82169c2689e1c4ad5994765556179eb2/backtesting/_stats.py#L138

Unless I am missing something?

Thanks!

Start in backtesting/_stats.py at the referenced lines 138-139 and compare the SQN calculation with the linked expectancy formula. Confirm whether the computed expectancy is omitted, then verify that the corrected SQN result matches the documented definition and the project's relevant checks.

Written by the indexing model from the issue text.