The Coppock Curve was developed by Edwin Sedgwick Coppock in 1962. It was featured in the November 94 issue of Technical Analysis of Stocks & Commodities, in the article "The Coppock Curve", written by Elliot Middleton:
Taken from Stocks & Commodities, V. 12:11 (459-462): The Coppock Curve by Elliott Middleton
"We are creatures of habit. We judge the world relative to what we have experienced. If we're shopping for a mortgage and rates have been in the teens (as they were in the early 1980s) and then drop to 10%, we are elated. If, however, they've been at 8% and then rise to 10%, we are disappointed. It all depends on your perspective.
The principle of adaptation-level applies to how we judge our income levels, stock prices and virtually every other variable in our lives. Psychologically, relativity prevails...
The moving average is the simplest form of adaptation-level. Moving average crossover rules accurately signal the onset of periods of returns outside the norm, whether positive or negative. This makes moving average crossovers useful to traders who want to get a boost on entering or exiting stocks or funds.
The oscillator is also based on adaptation-level, although in a slightly different way. Oscillators generally begin by calculating a percentage change of current price from some previous price, where the previous price is the adaptation-level or reference point. The mind is attuned to percentage changes because they represent returns. If you bought Microsoft Corp. stock (MSFT) at $50 and it goes to $80, you make 60% before dividends. If you bought Berkshire Hathaway (BRK) at $4,000 and it rises to $4,030, the same dollar gain, you make 0.75% before dividends. It's the percentage change that counts. Relativity again.
Coppock reasoned that the market's emotional state could be determined by adding up the percentage changes over the recent past to get a sense of the market's momentum (and oscillators are generally momentum indicators ). So if we compare prices relative to a year ago - which happens to be the most common interval - and we see that this month the market is up 15% over a year ago, last month it was up 12.5% over a year ago, and 10%, 7.5% and 5%, respectively, the months before that, then we may judge that the market is gaining momentum and, like a trader watching for the upward crossover of the moving average, we may jump into the market."
The MetaStockTM formula for the Coppock Curve is: