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Moving Averages 移动平均线: Page 3 of 4

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Exponential Moving Average (EMA) Explained

As we said in the previous lesson, simple moving averages can be distorted by spikes. We’ll start with an example.

Let’s say we plot a 5-period SMA on the daily chart of EUR/USD.

5-SMA on EUR/USD

The closing prices for the last 5 days are as follows:

Day 1: 1.3172

Day 2: 1.3231

Day 3: 1.3164

Day 4: 1.3186

Day 5: 1.3293

The simple moving average would be calculated as follows:

(1.3172 + 1.3231 + 1.3164 + 1.3186 + 1.3293) / 5 = 1.3209

Simple enough, right?

Well what if there was a news report on Day 2 that causes the euro to drop across the board. This causes EUR/USD to plunge and close at 1.3000. Let’s see what effect this would have on the 5 period SMA.

Day 1: 1.3172

Day 2: 1.3000

Day 3: 1.3164

Day 4: 1.3186

Day 5: 1.3293

The simple moving average would be calculated as follows:

(1.3172 + 1.3000 + 1.3164 + 1.3186 + 1.3293) / 5 = 1.3163

The result of the simple moving average would be a lot lower and it would give you the notion that the price was actually going down, when in reality, Day 2 was just a one-time event caused by the poor results of an economic report.

The point we’re trying to make is that sometimes the simple moving average might be too simple. If only there was a way that you could filter out these spikes so that you wouldn’t get the wrong idea. Hmm… Wait a minute… Yep, there is a way!

It’s called the Exponential Moving Average!

Exponential moving averages (EMA) give more weight to the most recent periods. In our example above, the EMA would put more weight on the prices of the most recent days, which would be Days 3, 4, and 5.

This would mean that the spike on Day 2 would be of lesser value and wouldn’t have as big an effect on the moving average as it would if we had calculated for a simple moving average.

If you think about it, this makes a lot of sense because what this does is it puts more emphasis on what traders are doing recently.

Exponential Moving Average (EMA) and Simple Moving Average (SMA) Side By Side

Let’s take a look at the 4-hour chart of USD/JPY to highlight how a simple moving average (SMA) and exponential moving average (EMA) would look side by side on a chart.

Exponential Moving Average

Notice how the red line (the 30 EMA) seems to be closer price than the blue line (the 30 SMA). This means that it more accurately represents recent price action. You can probably guess why this happens.

It’s because the exponential moving average places more emphasis on what has been happening lately. When trading, it is far more important to see what traders are doing NOW rather what they were doing last week or last month.

指数移动平均线

正如我们上节课讲到的,简单移动平均线走势能够受到价格短期内的巨幅波动而歪曲。

让我们看看欧元/美元5日移动均线。

汇价在过去5日的收盘价分别是:

第一天:1.3172

第二天:1.3231

第三天:1.3164

第四天:1.3186

第五天:1.3293

简单移动平均线计算结果如下:

(1.3172 + 1.3231 + 1.3164 + 1.3186 + 1.3293) / 5 = 1.3209

很简单,是吗?

那么,如果第二天有突发事件导致欧元/美元收盘下跌并收于1.3000呢。让我们看看这一变动对欧元/美元5日简单移动均线所造成的影响。

第一天:1.3172

第二天:1.3000

第三天:1.3164

第四天:1.3186

第五天:1.3293

简单移动均线计算结果将变为:

(1.3172 + 1.3000 + 1.3164 + 1.3186 + 1.3293) / 5 = 1.3163

这一简单移动均线的计算结果将较之前低很多,并可能给你造成这一印象,即价格实际上在走低,而实际上,第二天的价格走势只是受到糟糕经济数据影响而出现的单日事件。

我们需要指出来的是,简单移动均线有些时候可能过于简单。如果你能够滤除掉这些短期过度波动因素,那么你就不会得出错误的判断结论。

指数移动平均线就是一种方法!

指数移动平均线(EMA)给予最近时段的权重更大。在我们之前所给的例子中,指数移动均线将给予价格在最近几天更高的权重,这将是第三天、第四天和第五天。

这意味着价格在第二天的巨大波动并不会和我们通过简单移动均线计算的那样,对移动均线的走势造成大的影响。

如果你注意到这一点,这将是十分有意义的,因为指数移动均线所强调的是交易者最近的行为。

让我们看看美元/日元4小时图中,SMA和EMA在同一图形中的不同走势。

注意:红色曲线(30EMA)较蓝线(30SMA)更接近价格走势。这意味着,红色曲线更能代表近期的价格走势。你很可能能够猜出这是怎么发生的。

因为EMA更加强调最近的价格走势,近期交易者行为远要重要,而非是他们在上周或上个月的交易行为。