Novice Traders' Notebook  |  MAR 2002

Working Money: Average True Range by Sharon Yamanaka

Working Money: Average True Range by Sharon Yamanaka Average or extraordinary, “true range” is often referred to in stocks and commodities trading. But what is it? T rader, author, and technician J. Welles Wilder developed average true range (ATR) in the 1970s as a measurement of price volatility. Wilder believed that the range was directly proportional to volatility, and that range — the high and low of a stock for a given period, be it intraday, daily, weekly, or monthly — was indicative of a trend. If the volatility of a stock increased, it was entering a trend, and if it slowed down, it suggested a reversal. He further refined the trading range, calling it a true range when he included changes in price that occurred from the previous day’s close rather than starting from the opening price. Such things as after-hours announcements that would predispose the market to open higher or lower next day would not be accounted for.

by Sharon Yamanaka