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.

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) vs. Simple Moving Average (SMA)

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.

Notice how the red line (the 30 EMA) seems to be a 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 than what they were doing last week or last month.

Reprinted from Babypips，the copyright all reserved by the original author.