Just wanted to share a POC for the Probability State Indicator (PSI). Simon linked to it a while back

http://www.priceactionlab.com/Blog/2013/09/psi-the-probability-state-indicator/

Turns out it was fairly easy to reverse from the screenshot. It seems a little too simple but I'd be interested if anyone has a strategy for it. Basically, the closer the price is to the high of n periods, then the closer it is to 1. The inverse is true for the lows

```
delta = highest_high - lowest_low
delta_diff = highest_high - current_price
def calculate_psi(delta,delta_diff):
psi = (delta - delta_diff)/delta
return psi
```