Moving Averages（4）: Factors To Consider

By Casey Murphy, Senior Analyst ChartAdvisor.com

Data Used in Calculation （用于计算MA的数据）

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.

均线的计算通常是用资产的收盘价，但也不一定非得用收盘价。同样，开盘价、最高价、最低价甚至价格的中位数都可以用来计算均线。即使使用不同的数据来计算出来的均线之间或多或少会有些差异，但这些细微的差别仍然可以影响到你的分析（甚至决策）。

Finding an Appropriate Time Periods （寻找一个合适的时间周期）
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.

因为绝大多数均线表示的是每日数据的平均，因此需要指出的是，数据的长度不一定非得是以“天”为周期。MA同样可以用分钟、小时、周、月、季度甚至年作为时间周期进行计算。（不然）为什么一个日内交易员会去注意50日均线将怎样影响接下来几周的价格的变化？为什么会通过50分钟均线，与过去几小时比较证券的相对成本（这句话翻译得好烂……）？甚至有些交易员会拿过去三分钟的均线来衡量一次突破的短时动量。

No Average is Foolproof （MA并不是万无一失的）
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（it came close省略了when?）, 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.

如你所知，金融市场中nothing is for certain，技术指标也一样。如果股票价格触及它的支撑位（均线支撑）后，每次都能反弹，那我们都发了。均线的一个主要缺点在于，当资产价格盘整（横盘震荡…）时，它就不那么有效。

图1，横盘时，资产价格多次上下地穿过均线，令人捉摸不定，并不知道如何去交易……

因此：均线策略是一种趋势型的策略，但这种策略在震荡行情下基本失效。

Figure 1

Responsiveness to Price Action （对价格变动的响应）
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.

使用均线交易的交易员会毫不犹豫地承认，1）又要让均线快速反映趋势的变化，2）又不让均线对于价格的一丢丢变化就非常灵敏地响应，以至于让自己过早地进入或退出交易，是非常难的一件事。短时均线在一个强烈的趋势发生之前识别出趋势的变化相当有效，但缺点是这种技术可能会在开仓和平仓时对交易员造成双重损失，因为短时均线太过灵敏。不同时间周期的MA给出的交易信号之间的质量差异还是很大的，所以强烈建议和其他技术指标一同使用。

Beware of the Lag（警惕时滞！均线总是慢半拍）
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.

MA是一个具有延时特征的技术指标！总会慢半拍！这种滞后的特性可能使得交易员在最不合适的时候进行交易。

通俗地举个例子。价格突然上涨，过了一段时间以后，才出现了均线金叉。如果这个时候买入，说不定已经到了所谓的牛市的尾巴上了，于是……

Figure 2