Moving averages have long been a staple for tracking the course of a stock's price. But averages are only part of the story, variability is equally important. The deviations of current prices from the moving averages (of varying lengths) are widely used by investors as signals. Bands above and below the moving average have been used to designate unusually large variations, with various rules for interpreting these events as signals for future moves in price. Bollinger's unique contribution was to take not only the average price into account, but also the variation of the prices and creating bands of expanding and contracting size as the prices become more or less variable over a period of time. This adds a whole new dimension to the tracking of price movements.  He presents many examples and alternative interpretations of these Bollinger Bands. It is a valuable tool for anyone who relies on technical analysis to track and forecast price movements. As a rule, the more relavent information you can incorporate into a signal, the more effective it will be.

Bollinger on Bollinger Bands PDF

The list of books you might like