大多数移动平均线使用给定资产收盘时的价格用以计算。但是需要注意的是不是总是这样。移动平均线的计算可能选用开盘、收盘、高点、低点甚至是总价价格。尽管这些计算的区别很小，但是还是可能影响到你的分析。
找到合适的时间周期
因为大多数移动平均线代表所有计算日期的平均值，值得注意的是时间周期不总是使用天。移动平均线的计算可以使用分钟、小时、周、月、季度甚至是年。为什么一个当日交易员关心50天移动平均线对未来几周造成什么样的影响呢？在另一方面，当日交易员会注意50分钟移动平均线以用来和过去几个小时比较相对成本。一些交易员甚至过去三分钟的平均价格来判断短期动量。
移动平均线不是万无一失的
正如你所了解的，金融市场中没有任何事情是确定不变的，当然使用技术指标时也一样。如果股票每次都能在主要移动平均线反弹那么我们都能赚很多。使用移动平均线的一个主要缺点是当一个资产趋强烈时它的作用会不太明显。
对价格行为的反映
使用移动平均线的交易员将会快承认试图让一个移动平均线对趋势变化产生反映而不太敏感的让交易员过早的进入或者退出一个仓位将成为一个难题。短期移动平均线在大规模变化发生之前确定趋势变化会很有用，但是不利的是这这种技巧可能在进出仓位是造成双重损失，因为移动平均线对价格变化反映十分快快速。因为交易信号的质量将很大程度上取决于计算用的时间周期，所以我们非常建议使用其他技术指标确定移动平均线进行的预测。
警惕滞后性
因为移动平均线是滞后指标，交易信号总是发生在价格充分移动之后。这种滞后性对交易员十分不利可能导致他们在最不合适的时间进入仓位。例如，短期移动平均线交叉移动到长期移动平均线之上的唯一情况是最近价格在上升，许多交易员把这当成牛市信号。在这当中出现的最主要问题时在交叉之前价格很可能已经有大幅上涨。
Moving Averages: Factors To Consider
By Casey Murphy, Senior Analyst ChartAdvisor.com
Data Used in Calculation
Most moving averages take the closing prices of a given asset and factor them into the calculation. We thought it would be important to note that this does not always need to be the case. It is possible to calculate a moving average by using the open, close, high, low or even the median. Even though there is little difference between these calculations when plotted on a chart, the slight difference could still impact your analysis.
Finding an Appropriate Time Periods
Because most MAs represent the average of all the applicable daily prices, it should be noted that the time frame does not always need to be in days. Moving averages can also be calculated using minutes, hours, weeks, months, quarters, years etc. Why would a day trader care about how a 50-day moving average will affect the price over the upcoming weeks? On the other hand, a day trader would want to pay attention to a 50-minute average to get an idea of the relative cost of the security compared to the past hour. Some traders may even use the average price over the past three minutes to gauge an uptake in short-term momentum.
No Average is Foolproof
As you know, nothing in the financial markets is for certain - certainly not when it comes to using technical indicators. If a stock bounced off the support of a major average every time it came close, we would all be rich. One of the major disadvantages of using moving averages is that they are relatively useless when an asset is trending sideways, compared to the times when a strong trend is present. As you can see in Figure 1, the price of an asset can pass through a moving average many times when the trend is moving sideways, making it difficult to decide how to trade. This chart is a good example of how the support and resistance characteristics of moving averages are not always present.
Responsiveness to Price Action
Traders who use moving averages in their trading will quickly admit that there is a battle between trying to make a moving average responsive to changes in trend while not allowing it to be so sensitive that it causes a trader to prematurely enter or exit a position. Short-term moving averages can be useful in identifying changing trends before a large move occurs, but the downside is that this technique can also lead to being whipsawed in and out of a position because these averages respond very quickly to changing prices. Because the quality of the transaction signals can vary drastically depending on the time periods used in the calculation, it is highly recommended to look at other technical indicators for confirmation of any move predicted by a moving average. (For more on various indicators, see Introduction To Technical Analysis.)
Be ware of lagging
Because moving averages are a lagging indicator, transaction signals will always occur after the price has moved enough in one direction to cause the moving average to respond. This lagging characteristic can often work against a trader and cause him or her to enter into a position at the least opportune time. For example, the only way for a short-term moving average to cross above a long-term moving average is for the price to have recently moved higher - many traders will use this bullish crossover as a buy signal. One major problem that often arises is that the price may have already experienced a large increase before the transaction signal is presented.As you can see in Figure 2, the large price gap creates a buy signal in late August, but this signal is too late because the price has already moved up by more than 25% over the past 12 days and is becoming exhausted. In this case, the lagging aspect of a moving average would work against the trader and likely result in a losing trade. Check out the next section of this tutorial to learn about trading strategies involving moving averages.
本文翻译由兄弟财经提供
文章来源：http://www.investopedia.com/university/movingaverage/movingaverages3.asp