The presented indicator is prepared on the basis of well known indicator Bollinger Bands. In short, Bollinger Bands consists of two lines that are situated above and below of moving average plotted of a certain number of standard deviations away from it. In case of high volatility lines become wider, during less volatile periods they become narrower. So, these bands show borders of possible price movement.
Observation of the Bollingers behavior has revealed another interesting pattern. The widening of the channel indicates the formation of bullish or bearish type of the price movement. In my opinion it is not possible to find the starting point of such movement, because as a rule it becomes clear at the end. However, this moment may be adopted to find the point of extinction of the impulse. Figure 1 shows that the narrowing of the Bollinger Bands channel is correlated with the moment of the break in struggle between bears and bulls.
For traders convenience, it is prepared indicator, which calculates difference between upper and lower lines of Bollinger Bands, which is plotted in a separate window as a histogram. Because of the lack the description in the literature the indicator with a similar algorithm, for the purpose of this publication I decided to call it BoDi (Bollinger’s Difference) (Fig. 1).
Fig. 1. Indicator Bollinger Bands (on the chart) and BoDi (under chart)
Indicator is calculated on the following formulas:
1. Bollinger Bands:
D – number of standard deviations,
y – price for i bar,
n – number of periods used for calculations,
UpperBB and LoweBB – upper and lower lines of Bollinger Bands.
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