The Bollinger Bandwidth measures the difference between the upper and the lower bollinger Bands, as a percentage of the Moving Average. The indicator is calculated as follows:
Bandwidth = ((Upper Bollinger Band – Lower Bollinger Band) / Moving Average) * 100
The Bollinger Bandwidth is used to measure volatility. During periods of high share price volatility, the Bandwidth is wider, and vice versa.
Parameters
Type - Which type of Moving Average to use as the denominator in the formula. Simple, Exponential, or otherwise.
Period - How many periods (eg. days) to lookback when calculating the Moving Average (see Type).
Field - Which price field to use to calculate the Moving Average (eg. Close Price)
**Standard Deviation - **How many standard deviations the upper (and lower) Bollinger Bands should be plotted above (and below) the Moving Average.