John Bollinger created a tool to analyze prices in currency pairs. This tool he created in the 1980’s would come to be eventually known as the Bollinger bands. To understand how they work and how you can use it in technical analysis of a Forex market currency pair, it is useful to know a little about moving averages. A moving average, also known as a rolling average used with a sequence of best fit price points measured at successive uniform time intervals, will show you the short-term fluctuations and longer-term trends or cycles in a currency pair. You may wonder to what end or with what objective, well the moving average will chart a smoother curve based on previous price points making it easier for you as a trader to spot a change in the trend of the currency pair, and confirm support and resistance levels of the currency pair at a given time when used in conjunction with other tools and indicators.
Also since moving averages are only computed at specific intervals, they are immune to price spikes that the Forex is known for, hence the smooth curve. The types of moving averages most commonly used in the Forex market by analysts is the simple moving average (SMA) and the exponential moving average (EMA). Right, so with Bollinger bands you have your middle graph set to plot using a moving average of typically 20 or 50 closed price levels. Notice there a no units for the interval as this depends on what kind of trader you are for instance a ‘scalper’ or intraday trader will be interested in 20 previous price points within the hour as opposed to a long term trader who may use 20 weeks or even 20 months.
In addition to the middle graph you will have 2 more graphs that trace beside the MA20 graph at 2 standard deviations, above and below it to form what is known as the ‘envelope’; you should know that these are arbitrary figures and you are free to choose your own deviations and moving average to use for the bands but 20 SMA is normally recommended for beginning technical analysts.
So now that we know what they are and how they work, how can we use them in analysis? One thing to remember is that Bollinger bands like all other tools are not absolute, because they can only give you the best buy and the best sell signals of a currency pair based on relative information and indicators at a particular time with all things constant; the decision to buy or to sell would still require your better judgment in the interpretation of the information that the bands would illustrate. The lower Bollinger band often (not always) provides price level support while the upper Bollinger band provides price level resistance. As much as Bollinger himself categorically stated that if the price level of the currency pair tags or exceeds any of the deviated bands, it does not indicate a buy/sell signal, millions of traders in the Forex market do not adhere to his doctrine.
Try it for yourself by placing a Bollinger band envelope of a EUR/USD chart and watch the price levels shift as they approach the lower or upper graphs, what you want to look for is the closing low/highs of the candle sticks immediately preceding the one that breaks either the upper or lower bands.
In conclusion, as a simple strategy you can monitor the price levels as they approach the upper and lower bands, and wait for them to breakout. When this happens they will usually retrace back and ‘range’ ; and depending on the previous candlestick when the break from the Bollinger band envelope occurred and the ranging begun (that is whether the candle stick’s open and close levels are lower than the previous candle stick), you can consider that an alert that a major price shift is about to occur. It will be up to you to then decide whether to take a position.