Visually see how well a symbol tracks another's movements, without taking price deltas into account.
For example, a 1% move on the index and a 5% move on the target will return a DCC value of 1. An index move of 0.5% on the index and a 10% move on the target will also return a DCC value of 1. The same happens for downward moves.
The SMA value can be set to smooth the curve. A larger value creates a smoother curve.