“…The reduced form of the GarmanKlass volatility estimator can be written as 5 (4) where P t,H , P t,L , P t,O , and P t,C are the high, low, opening, and closing futures prices at date t, respectively. Wiggins (1992) and Daigler and Wiley (1999) showed that the Garman-Klass volatility estimator is more efficient than using close-to-close prices. To match the weekly COT data, the daily volatility estimate is averaged over the WednesdayTuesday interval, and used as the dependent variable in equation (1).…”