Bollinger Bands

Bollinger Bands measure volatility by plotting a series of three bands. The middle band represents the moving average (Simple Moving Average or Weighted Moving Average orExponential Moving Average). The upper band is a set number of standard deviations higher than the middle band (generally 2), and the lower band is a set number of standard deviations (generally 2) lower than the middle band. You set the distance of standard deviation when you create the study.