Registered User
Joined: 12/21/2008
Posts: 8
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Worden Trainer
Joined: 10/7/2004
Posts: 65,138
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The formula for Bollinger %b depends on the Period and Width of the Bollinger Band for which it is being calculated. The following represents a Bollinger %b 20,20 where the Lower BB is 0 and the Upper BB is 100:
100 * (C - AVGC20) / SQR(ABS(C ^ 2 + C1 ^ 2 + C2 ^ 2 + C3 ^ 2 + C4 ^ 2 + C5 ^ 2 + C6 ^ 2 + C7 ^ 2 + C8 ^ 2 + C9 ^ 2 + C10 ^ 2 + C11 ^ 2 + C12 ^ 2 + C13 ^ 2 + C14 ^ 2 + C15 ^ 2 + C16 ^ 2 + C17 ^ 2 + C18 ^ 2 + C19 ^ 2 - 20 * AVGC20 ^ 2) / 19) / 4 + 50
You may wish to review the following:
Modelling Bollinger Bands (& Standard Deviation) in a TC PCF
How to create a Personal Criteria Forumula (PCF)
PCF Formula Descriptions
Handy PCF example formulas to help you learn the syntax of PCFs!
-Bruce
Personal Criteria Formulas
TC2000 Support Articles
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Registered User
Joined: 12/21/2008
Posts: 8
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How would you write the PCF so that it would give stocks that pierce the lower BB rather than the upper one?
Thanks
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Worden Trainer
Joined: 10/7/2004
Posts: 65,138
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The formula given isn't Boolean, it just returns where it is in the bands (so if the result is less than 0, it is below the Lower BB). You could write a Personal Criteria Formula for Price being below the Lower Bollinger Band 20,20 as:
C < AVGC20 - 2 * SQR(ABS(C ^ 2 + C1 ^ 2 + C2 ^ 2 + C3 ^ 2 + C4 ^ 2 + C5 ^ 2 + C6 ^ 2 + C7 ^ 2 + C8 ^ 2 + C9 ^ 2 + C10 ^ 2 + C11 ^ 2 + C12 ^ 2 + C13 ^ 2 + C14 ^ 2 + C15 ^ 2 + C16 ^ 2 + C17 ^ 2 + C18 ^ 2 + C19 ^ 2 - 20 * AVGC20 ^ 2) / 19)
-Bruce
Personal Criteria Formulas
TC2000 Support Articles
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