文档介绍：Subject: Technical Stock Analysis
Bollinger Bands
Developed by John Bollinger, Bollinger Bands allows users pare volatility and relative
price levels over a period time. Bollinger Bands are envelopes which surround the price bars on a
chart. They are plotted two standard deviations away from a simple moving average. Because
standard deviation is a measure of volatility, the bands adjust themselves to ongoing market
conditions. They widen during volatile market periods and contract during less volatile periods.
Bollinger Bands are, essentially, moving standard deviation bands.
Bollinger Bands are sometimes displayed with a third center line. This is the simple moving
average line. Mr. Bollinger mends using a 10 day moving average for short term trading,
20 days for intermediate term trading, and 50 days for longer term trading.
The standard deviation value may be varied. Increase the value of the standard deviation from 2
standard deviations to 2-1/2 standard deviations away from the moving average when using a 50
day moving average. Conversely, lower the value of the standard deviation from 2 to 1-1/2
standard deviations away from the moving average when using a 10 day moving average.
Bollinger Bands do not generate buy and sell signals alone. They should be used with another
indicator. I use them with RSI, described below. This is because wh