Elder-Ray Index

What Is the Elder-Ray Index?

The Elder-Ray Index is a technical indicator developed by Dr. Alexander Elder that measures the amount of buying and selling pressure in a market. This indicator consists of two indicators known as "bull power" and "bear power," which are derived from a 13-period exponential moving average (EMA). These, along with the EMA, help traders determine the trend direction and isolate spots to enter and exit trades.

Understanding the Elder-Ray Index

Technical traders will use the values of bull and bear power, along with divergence, to make trading decisions. Long positions are taken when the bear power has a value below zero but is increasing, and the bull power's latest peak is higher than it was previously (rising). A short position is taken when the bull power value is positive but falling, and the bear power's recent low is lower than it was previously (falling).

The slope of the EMA can also be used in both cases to help confirm the direction of the trend. Traders can watch for the bull and bear signals and then wait for the EMA to start moving in the anticipated direction before taking a trade, or sometimes the EMA will already be moving in a particular direction and then the bull/bear power indicators will provide a confirming trade signal.

Dr. Elder's original methodology generally uses a 13-day exponential moving average (EMA) to gauge the market's consensus of value. This may be altered based on personal preference, and Elder himself utilized 26-day EMAs when analyzing weekly charts. Bull power measures the ability of buyers to drive prices above the consensus value, while bear power measures the ability of sellers to push prices below the consensus value.

Most charting platforms require three windows to be open on one chart when using the Elder-Ray approach.

1. Window one includes a bar or candlestick chart with the 13-period exponential moving average.
2. Window two shows the Elder-Ray Bull Power indicator.
3. Window three shows the Elder-Ray Bear Power indicator.

Elder-Ray Index Calculation

$\begin{aligned} &\text{Bull Power} = \text{Period High} - \text{13 Period EMA} \\ &\text{Bear Power} = \text{Period Low} - \text{13 Period EMA} \\ &\textbf{where:} \\ &\text{Period High and Period Low} = \text{High or low price for the} \\ &\text{time period used, such as a daily chart or a 1-hour chart} \\ &\text{EMA} = \text{Exponential Moving Average} \\ \end{aligned}$​Bull Power=Period High−13 Period EMABear Power=Period Low−13 Period EMAwhere:Period High and Period Low=High or low price for thetime period used, such as a daily chart or a 1-hour chartEMA=Exponential Moving Average​

1. Calculate the 13-period EMA for the time period being used. If using a daily chart, for example, calculate the EMA based on the last 13 days.
2. Find the period-high price and subtract the 13-period EMA from it to get the bull power value.
3. Find the period-low price and subtract the 13-period EMA from it to get the bear power value.
4. Repeat steps one through three each time a period ends.

Elder-Ray Index Vs. Average Directional Index (ADX)

The average directional index (ADX) is derived from the Positive Direction Index (+DI) and Negative Direction Index (-DI) which measure bullish and bearish movement similar to the bull and bear power indicators. The main difference is that +DI and -DI are smoothed averages divided by the average true range (ATR). While all these indicators are measuring upward and downward movement, the calculations are quite different and therefore will look different and provide different trade signals on a chart.

Limitations of Using the Elder-Ray Index

The Elder-Ray Index may be prone to whipsaws, as the bull and bear power indicators will often oscillate above and below zero.

Since the Elder-Ray Index uses a moving average, it is naturally a lagging indicator (although Elder himself called it an oscillating indicator) as it is based on historical price data. Therefore, it may react slowly to price changes. A sell signal, for example, may occur after the price has already dropped significantly—which can be problematic if you are using the indicator for buy and sell signals. To help fix this problem, set stop-loss orders at the time of the trade to help control risk.

Ideally, it's best not to use the Elder-Ray Index in isolation. Rather, combine it with other forms of analysis, such as price action trading, other indicators, or chart patterns.