xjo direction, page-45

Coppock is better at bottoms than tops but lags a bit.

The Coppock curve or Coppock indicator is a technical analysis indicator for long-term stock market investors created by E.S.C. Coppock, first published in Barron's Magazine in October 15, 1962.[1]

The indicator is designed for use on a monthly time scale. It's the sum of a 14-month rate of change and 11-month rate of change, smoothed by a 10-period weighted moving average.

Calculate 11 period Rate of Change (price)
Calculate 14 period Rate of Change (price)
Add the results of both
Calculate a 10 period weighted moving average of the result