The Average Directional Index (ADX) helps one understand the strength of a trend. It is a momentum indicator that is derived from the moving average of the 14-day period. It is well supported by two other indicators -- Positive Directional Indicator (+D) and the Negative Directional Indicator (-D) that are derived from moving averages and true range. The ADX is read on the scale of 0-100; ADX trading above 25 value is considered as a bullish signal and below 25 as negative strength.
The ADX determines the strength of a trend, whereas the +D and –D identify the trend direction.

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