The Mass Index was designed to identify trend reversals by measuring the narrowing and widening of the range between the high and low prices. As the range widens the Mass Index increases; as the range narrows the Mass Index decreases. The MASS Index appeared in the June 92 Technical Analysis of Stocks & Commodities article "The Mass Index", by Donald Dorsey. Taken from Stocks & Commodities, V. 10:6 (265-267): The Mass Index by Donald Dorsey "Range oscillation, not often covered by students of technical analysis, delves into repetitive market patterns during which the daily trading range narrows and widens. Examining this pattern, Donald Dorsey explains, allows the technician to forecast market reversals that other indicators may miss. Dorsey proposes the use of range oscillators in his mass index." The following is the MetaStock formula for the Mass Index: Sum(Mov( ( H - L ) ,9 ,E) / Mov(Mov( ( H - L ) ,9 ,E) ,9 ,E ) ,25 )