Those of you who have followed my work for some time know that I take a "toolbox" approach to analyzing and trading markets. The more technical and analytical tools I have in my trading toolbox at my disposal, the better my chances for success in trading. One of my favorite tools is moving averages. First, let me give you an explanation of moving averages, and then I’ll tell you how I use them.

Moving averages are one of the most commonly used technical tools. In a simple moving average, the mathematical median of the underlying price is calculated over an observation period. Prices (usually closing prices) over this period are added and then divided by the total number of time periods. Every day of the observation period is given the same weighting in simple moving averages. Some moving averages give greater weight to more recent prices in the observation period. These are called exponential or weighted moving averages. In this educational feature, I’ll only discuss simple moving averages.

The length of time (the number of bars) calculated in a moving average is very important. Moving averages with shorter time periods normally fluctuate and are likely to give more trading signals. Slower moving averages use longer time periods and display a smoother moving average. The slower averages, however, may be too slow to enable you to establish a long or short position effectively.

Moving averages follow the trend while smoothing the price movement. The simple moving average is most commonly combined with other simple moving averages to indicate buy and sell signals. Some traders use three moving averages. Their lengths typically consist of short, intermediate, and long-term moving averages. A commonly used system in futures trading is 4-, 9-, and 18-period moving averages. Keep in mind a time interval may be ticks, minutes, days, weeks, or even months. Typically, moving averages are used in the shorter time periods, and not on the longer-term weekly and monthly bar charts.

The normal moving average "crossover" buy/sell signals are as follows: A buy signal is produced when the shorter-term average crosses from below to above the longer-term average. Conversely, a sell signal is issued when the shorter-term average crosses from above to below the longer-term average.

Another trading approach is to use closing prices with the moving averages. When the closing price is above the moving average, maintain a long position. If the closing price falls below the moving average, liquidate any long position and establish a short position.

Here is the important caveat about using moving averages when trading futures markets: They do not work well in choppy or non-trending markets. You can develop a severe case of whiplash using moving averages in choppy, sideways markets. Conversely, in trending markets, moving averages can work very well.

In futures markets, my favorite moving averages are the 9- and 18-day. I have also used the 4-, 9- and 18-day moving averages on occasion.

When looking at a daily bar chart, you can plot different moving averages (provided you have the proper charting software) and immediately see if they have worked well at providing buy and sell signals during the past few months of price history on the chart. I will point out moving averages to my readers when they have been effective in a given market. If I see that moving averages have not been effective in a given market, I’ll likely ignore them.

I said I like the 9-day and 18-day moving averages for futures markets. For individual stocks, I have used (and other successful veterans have told me they use) the 100-day moving average to determine if a stock is bullish or bearish. If the stock is above the 100-day moving average, it is bullish. If the stock is below the 100-day moving average, it is bearish. I also use the 100-day moving average to gauge the health of stock index futures markets.

One more bit of sage advice: A veteran market watcher told me the "commodity funds" (the big trading funds that many times seem to dominate futures market trading) follow the 40-day moving average very closely. Thus, if you see a market that is getting ready to cross above or below the 40-day moving average, it just may be that the funds could become more active.