mass index

The mass index is an indicator, developed by Donald Dorsey, used in technical analysis to predict trend reversals. It is based on the notion that there is a tendency for reversal when the price range widens, and therefore compares previous trading ranges (highs minus lows). Mass index for a commodity is obtained by calculating its exponential moving average over a 9-day period and the exponential moving average of this average (a "double" average), and summing the ratio of these two over a given number of days (usually 25). Generally the EMA and the re-smoothed EMA of EMA are fairly close, making their ratio is roughly 1 and the sum around 25.