BBW (Bollinger BandWidth)¶
What it shows: how wide the Bollinger Bands are, as a percent of the middle line. It also tracks the lowest and highest width over a longer window, and %BandWidth: how today's width ranks against that window (0 = narrowest, 100 = widest).
How people use it: very narrow bands (a "squeeze") often come before a big move; traders watch for the width at its lowest and then trade the breakout. Width at its highest shows an expansion that may be running out.
Pairs well with: a direction signal, such as price crossing a Bollinger Bands band or a Donchian Channels breakout, because BandWidth says nothing about direction.
Settings¶
| Setting | Default | What it does |
|---|---|---|
| Length | 20 | Length of the Bollinger Bands. |
| Std dev | 2.0 | Width of the bands. |
| Squeeze lookback | 125 | How many candles the lowest / highest width and %BandWidth look at. Longer makes a "squeeze" rarer. |
| Lookback (bars) | 5 | How many candles back "rising" and "falling" compare with. |
You set the defaults on the Indicators page. A condition can use its own settings, which override the defaults for that condition only.
Ready-made conditions¶
| For | Condition | Fires when |
|---|---|---|
| Buy or sell | BandWidth at its 125-bar low (squeeze) | every candle BandWidth is at or below the Lowest BandWidth line |
| Buy or sell | BandWidth at its 125-bar high (expansion) | every candle BandWidth is at or above the Highest BandWidth line |
| Buy or sell | %BandWidth below 10 (narrow vs the last 125 bars) | every candle %BandWidth is below 10 |
| Buy or sell | %BandWidth above 90 (wide vs the last 125 bars) | every candle %BandWidth is above 90 |
| Buy or sell | BandWidth rising (vs 5 bars ago) | every candle BandWidth is higher than 5 candles before |
| Buy or sell | BandWidth falling (vs 5 bars ago) | every candle BandWidth is lower than 5 candles before |
"Above", "below", "is" and "rising" / "falling" stay true on every candle the state lasts, so they can fire many candles in a row. Numbers in the condition names follow your settings on the Indicators page.
Warnings you may see¶
- "BBW(20,2,125) %BandWidth only moves between 0 and 100, so 200 can never be reached.": a number you typed is outside the range this line can take, so the condition can never be true (or is always true). Check the number. You can still save it.
- "It compares a line with itself (same indicator, same settings), so it can never fire. Give the two lines different settings.": both sides of the condition are the very same line. Pick a different line or different settings for one side. With ">=", "<=", "==" or "touches" the message ends "so it is always true" instead.
- "Length must be between 1 and 1000" / "Length must be a whole number": shown in the condition editor when a condition's own value is out of range. Fix the number; the condition can't be saved until then.
- "Std dev must be between 0.1 and 10": shown in the condition editor when a condition's own value is out of range. Fix the number; the condition can't be saved until then.
- "Squeeze lookback must be between 1 and 1000" / "Squeeze lookback must be a whole number": shown in the condition editor when a condition's own value is out of range. Fix the number; the condition can't be saved until then.
Where they show: on the Strategies page, open Create entry conditions / Edit entry conditions (or the exit ones). Each condition's messages appear right under it. The setting messages ("must be between", "whole number", "must be one of", "must be smaller than") start with the indicator's short name, for example "MACD: Fast must be between 1 and 1000", and keep the conditions from being saved until fixed. The other warnings never block saving and are repeated in the strategy's Entry or Exit section, starting with the condition's name.
Good to know¶
- It is worked out from closing prices only (not volume).
- It needs some history before its value settles: the length + Squeeze lookback candles (145 at the defaults). Apathia loads that history for you.
- BandWidth shows no direction, so the same conditions are offered for buys and sells.