by Bob Stokes
Updated: November 18, 2013
The moving average is a technical indicator which has stood the test of time. It's been 27 years since Robert Prechter described this vital tool in his famous essay, "What a Trader Really Needs to be Successful." What he said then remains true today:
A simple 10-day moving average of the daily advance-decline net, probably the first indicator a stock market technician learns, can be used as a trading tool, if objectively defined rules are created for its use.
What is a moving average? Here's how EWI's Jeffrey Kennedy puts it:
A moving average is simply the average value of data over a specified time period, and it is used to figure out whether the price of a stock or commodity is trending up or down.
He also says that you can think of a moving average as an automated trend line.
A 20-year veteran of technical analysis, Jeffrey wrote "How You Can Find High-Probability Trading Opportunities Using Moving Averages."
[Descriptions of the following charts are summaries from that eBook]:
Let's begin with the most commonly-used moving averages among market technicians: the 50- and 200-day simple moving averages. These two trend lines often serve as areas of resistance or support.
For example, the chart below shows the circled areas where the 200-period SMA provided resistance in an April-to-May, 2008 upward move in the DJIA (top circle on the heavy black line), and the 50-period SMA provided support (lower circle on the blue line).
Let's look at another widely used simple moving average which works equally well in commodities, currencies, and stocks: the 13-period SMA.
In the sugar chart below, prices crossed the line (marked by the short, red vertical line), and that cross led to a substantial rally. This chart also shows a whipsaw in the market, which is circled.