As
in any other indicator, the period selected is a critical element. The
shorter the period the more sensitive the MA is to price movements and
is less consistent, and the larger the period chosen, the more
consistent it is, but at the same time less sensitive to price
fluctuations.
The moving average explained above is called simple moving average (SMA). However, there are also other popular types of moving averages: exponential moving average (EMA) and weighted moving average (WMA).
The only difference between the SMA and the other two approaches is the
weight assigned to each period. EMA´s and WMA´s assign more weight to
the periods that are closer to the current price, while in SMA all
periods are equally weighted.
[Chart 1]
Let’s concentrate on
the yellow box. The green line is a 10 period exponential moving
average (EMA) while the red one is a 10 period simple moving average
(SMA). At the beginning of the yellow box there is a small period of
consolidation where moving averages are pretty close to each other, there is nothing to be noticed. But once the market starts moving, you will see the EMA(10) lifts up first, then
the SMA(10). This is because the EMA gives more weight to periods
closer to the market action than SMA’s. This means that EMA’s will
always be closer to the current market action than SMA.
Which one to use?
We prefer to use EMA since they give more value to more recent
price fluctuations, and reflect what is happening at any given time
with more accuracy. However, there are traders that prefer to use SMA.
Usage of Moving Averages
Usage No. 1 - As stated before, MA´s are trend following indicators.
They smooth out price fluctuations and make it easier to identify a
trend. There are several ways in which this indicator can be used to
identify the trend:
1 - Location of the MA in relation to price action. If the MA is above the price, it indicates a downtrend is in place. If the moving average is below the price then it is considered an uptrend.
2 - With the slope of the MA.
When the MA is sloping up, the market is considered to be in an
uptrend. When it is sloping down the market is considered to be in a
downtrend. When there is no slope (close to a flat line), then the
market is trendless or sideways
[Chart 2]
The
chart above shows both ways to identify a trend. When the price breaks
the EMA(21), a significant change in trend could be imminent (or at
least a retracement or consolidation period). Also the slope of the
EMA(21) keeps good track of the trend. There are also periods of
indecision (when the market breaks the MA back and forth). During these
periods, the EMA(21) could lead us to take false conclusions about the
market condition [when the EMA(21) is almost flat.]
For
this reason it is always advised to use a second MA. This allows us to
keep track of the location of one MA relative to the other. When the
short period MA is above the longer period MA the trend is considered an
uptrend, and when the short period moving average is below the larger
period MA, the trend is considered to be a downtrend.
[Chart 3]
In this case we added an EMA(75) [red line]. When the EMA(21) [green line] is above the EMA(75) [red line]
the trend is considered an uptrend (which is the case for the chart
above). On the other hand, when the EMA(21) is below the EMA(75) then
the trend is considered to be a downtrend.
Usage No. 2 - MA as support and resistance.
Some MA’s are used to establish levels of support and resistance. The
most common periods used in MA for this kind of usage are: 50, 100, 200,
144, 89, and 34.
[Chart 4]
In
this chart we used an EMA(144) [notice it is the same chart we used for
the other MA’s examples]. As you can see this moving average is a very
powerful price level in the chart. Almost all the time, something
happens when the price action approaches to
this EMA, either it bounces off from it or makes a wild break out. This
EMA(144) is significant on all charts and all time frames, we
personally use it a lot as a very important level of support and
resistance.
Usage No. 3 - Moving averages as cross-over signals.
Perhaps the most common and easy trading system is this one. It
consists in plotting a short period moving average and a larger period
moving average. When the short period moving average crosses above the
large period moving average, it signals a buy signal. When the short
period MA crosses down the larger period moving average, it indicates a sell signal.
[Chart 5]
In
the chart above we used an EMA(21) as the short period MA (red line)
and an EMA(34) as the longer period MA (green line). There are a total
of 5 cross-over signals: 3 buy and 2 sell signals. The three buy signals
are generated when the short period MA crosses above the long period MA
while the 2 short signals are generated when the short period MA
crosses below the long period MA.
Combination of Moving Averages Signals
During
trending conditions these types of systems work very well, getting you
in the market early and letting you catch most of the move. But during
consolidation periods, a moving average crossover gives many false
signals.
For
this reason is important to determine ahead of time the trend on each
trading possibility. If there is an existing trend, then we use a system
that works during trending conditions, if there is no trend, then we
use a system that works under ranging conditions.
Let’s
try to filter signals on the crossover above with a longer period
moving average that will be of use to us as trend identification.
[Chart 5]
What
we are trying to accomplish with this new large period MA is to filter
out signals against the trend. We are using the new EMA(75) as a trend
identification – position of the market in relation to the MA. According
to this new rule, most of the time the market stays above the EMA(75)
indicating an uptrend. What we are going to do now is to validate all
long signals and ignore all short signals as they are against the
direction of the trend and we know this system works best during
trending conditions taking trades in direction of the trend. So
we filter out all short signals and go ahead only with long signals.
This produces better results than taking every single signal.
Remember
also that the signals given by a MA crossover are very sensitive to the
number of periods chosen for the MA´s. If short periods of MA´s are
chosen, then the system is going to get you in the market early but also
will give you many false signals. On the other hand, if larger periods
are chosen, the system will get you in the market later, (giving up some
profits) but will give you more accurate signals.
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