Developed by Marc Chaikin. Look for sharp increases in volatility prior to market tops and bottoms, followed by low volatility as the market loses interest.
The Choppiness Index is a volatility indicator developed by Australian commodity trader Bill Dreiss to indicate whether a market is trending or ranging.
Bollinger's Bandwidth Indicator is used to warn of changes in volatility. A squeeze, where the bands converge into a narrow neck, often precedes a sharp price rise or fall.