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How Bollinger Bands Works

Bollinger Bands indicator calculations uses standard deviations to draw the bands, the default value used is 2.

Bollinger Bands Calculation

middle Bollinger band technical indicator line is a simple moving average

The upper band indicator is: Middle line + Standard Deviations

The lower Bollinger band indicator is: Middle line - Standard Deviation

Bollinger Bands indicator considers the best default moving average MA to calculate the Bollingers to be 20 price periods moving average and the bands are then overlaid on the chart price action.

Standard Deviation is a statistics concept. It originates from the theory notion of normal distribution. One standard deviation away from the mean either plus or minus, will enclose 67.5 % of all price action movement. Two standard deviations away from the mean either plus or minus, will enclose 95 % of all price action movement.

Using Bollinger Bands for Stock Trading - Bollinger Bands account for price movements within two standard deviations, capturing 95% of all price action. Only 5% falls outside these bands, making them useful for determining potential entry or exit points when prices approach the outer bands.

The Bollinger Band main function is to measure the price action volatility. What the Bollinger bands upper & lower limits try to do is to confine price action of up to 95 % of the possible closing prices.

Bollinger Bands compares the present closing price with the moving average MA of the closing price. The difference between these 2 prices is the volatility of the prevailing market price compared & analyzed to the MA. The price volatility will increase/decrease the standard deviations of the bollinger bands trading indicator.

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