The Basic Understanding of Bollinger Bands
📍 Strategy: Bollinger Bands measure deviation and can be helpful in diagnosing trends. By generating two sets of bands using different standard deviation parameters, traders can gauge trends and define buy and sell zones. The bands adapt dynamically to price action, widening and narrowing with volatility to create an accurate trending envelope. A touch of the upper or lower band is not a signal in and of itself, and attempting to "sell the top" or "buy the bottom" can lead to losses. Standard deviation is a statistical measure of the amount of variation or dispersion of a set of prices or returns from its average value. The higher the standard deviation, the wider the Bollinger Bands, indicating greater price volatility, and vice versa. Traders may use standard deviation to set stop-loss and take-profit levels or to help determine the risk-to-reward ratio of a trade.
📍 Calculation: First, calculate a simple moving average. Next, calculate the standard deviation over the same number of periods as the simple moving average. For the upper band, add the standard deviation to the moving average. For the lower band, subtract the standard deviation from the moving average.
Typical values used:
Short term: 10 day moving average, bands at 1.5 standard deviations. (1.5 times the standard dev. +/- the SMA)
Medium term: 20 day moving average, bands at 2 standard deviations.
Long term: 50 day moving average, bands at 2.5 standard deviations.
