Models — Arch

Yet, until Robert Engle introduced ARCH in 1982 (earning him the 2003 Nobel Prize), most econometric models did exactly that for financial data.

If you work in trading, risk, or quantitative finance, GARCH(1,1) should be as familiar to you as linear regression. It is the baseline—the "check your assumptions" model for anything involving volatility. arch models

[ \sigma_t^2 = \omega + \alpha \epsilon_t-1^2 + \beta \sigma_t-1^2 ] Yet, until Robert Engle introduced ARCH in 1982

For decades, standard statistical models assumed something called homoscedasticity —a fancy way of saying "constant variance." But financial returns are clearly heteroscedastic (changing variance). or quantitative finance

Beyond the White Noise: Why Financial Markets Need ARCH and GARCH Models