We present an econometric method for estimating the parameters of a diffusion model from discretely sampled data. The estimator is transparent, adaptive, and inherits the asymptotic properties of the generally unattainable maximum likelihood estimator. We use this method to estimate a new...

We present an econometric method for estimating the parameters of a diffusion model from discretely sampled data. The estimator is transparent, adaptive, and inherits the asymptotic properties of the generally unattainable maximum likelihood estimator. We use this method to estimate a new...

This essay examines what volatility tests tell us about the data and what implications we should derive from them. It argues that volatility tests do not tell us that "prices are too volatile", implying that "markets are inefficient", but rather that "(discounted) returns are forecastable",...