ROBERT F. ENGLE III

An American economist who won the 2003 Nobel Memorial Prize in Economics, along with Clive Granger, for his analysis of time-series data with time-varying volatility. Time-varying volatility is the fluctuation over time of the value of financial instruments, and Engle's discoveries of the variations in these instruments' volatility levels have become crucial tools for researchers and financial analysts alike. The model he developed is called autoregressive conditional heteroskedasticity, or ARCH.