when surfers scan the vast expanse of the ocean they are looking for the wave whose direction and pull assure them of an exhilarating ride but how do surfers know which building upsurge of water won t amount to much while others that look the same to beginners will pick them up and carry them in the answer lies in reading the direction and strength of the waves much like how traders navigate the financial markets enter the directional movement index dmi which is often a trusted way for technical analysts and traders to do much the same with the pricing currents of the market 
the dmi helps traders determine the strength and direction of price trends developed by j welles wilder in 1978 the dmi identifies the direction in which an asset price is moving the dmi does this by comparing earlier highs and lows and drawing two lines a positive directional movement line called di and a negative directional movement line called di a third line the average directional index adx can also gauge the strength of upward or downward trends 1