The Relationship Between the Moving Average Speed and Market Noise

The slower the moving average, the less it is going to be fooled by noise. The longer calculation period makes a single day less important and the average more able to hold onto the longer-term direction.
Some markets have more noise that others. The high-volume index markets have the most noise and, if you’re going to find the trend, you’ll need to take a very long view of those price moves. Foreign exchange markets and stock sectors have less noise and can be traded with a somewhat faster trend (medium speed is considered to be 25 to 60 days).
If you use a very fast trend, then you’ll want to take profits as often as possible since noise causes prices to change direction unexpectedly If you can’t expect prices to trend, then you must take profits often.
To summarize the way you need to look at a trading method based on long-term and short-term trends, remember that the short term is strongly influenced by noise, while the long term makes noise appear less important:
Short-Term Trend
Noise dominates short-term price movement.
Take profits often because noise causes sudden changes of direction.
Expect many small profits and a few large losses.
Use daily or intraday data.

Long-Term Trend
Noise is small compared to the length of the trend.
Stay with the trend, and don’t take profits. Take advantage of the fat tail.
Expect many small losses and a few large profits.
Use daily or weekly data.