Price Expansion and Contraction is basic calculation of Candles High-Low and it is average of previous 5 High-Low. Which will help to analyse volatility of running situation. This can be used for analysis purpose only not as buy/sell signals.
How to use this?
Ranges of candles may increase on lower value of PEC.
Ranges of candles may decrease on high of PEC.
This is not ATR of 5 period.