Lagging indicator
An indicator whose value is derived entirely from prices that have already happened, so it changes after the movement does.
How to read the number
The delay is not a flaw in the arithmetic but its definition: averaging the past cannot, by construction, get ahead of the present.
When the metric lies
The size of the delay grows with the period and peaks at a turn — exactly where most is asked of the indicator.
Also known as: lagging signal