مقایسهٔ روش‌ها

	مدل TGARCH (آستانه GARCH)	مدل EGARCH (نمایی GARCH)
حوزه	اقتصادسنجی	اقتصادسنجی
خانواده	Regression model	Regression model
سال پیدایش	1993-1994	1991
پدیدآور	Zakoian (1994); Glosten, Jagannathan & Runkle (1993)	Daniel B. Nelson
نوع	Asymmetric volatility model	Volatility / conditional variance model
منبع بنیادین	Zakoian, J.-M. (1994). Threshold heteroskedastic models. Journal of Economic Dynamics and Control, 18(5), 931-955.	Nelson, D. B. (1991). Conditional heteroskedasticity in asset returns: A new approach. Econometrica, 59(2), 347–370.
نام‌های دیگر	Threshold GARCH, TGARCH, GJR-GARCH, asymmetric GARCH	Exponential GARCH, EGARCH, Nelson EGARCH, log-GARCH
مرتبط	6	6
خلاصه	The Threshold GARCH (TGARCH) model extends the standard GARCH framework by allowing positive and negative return shocks to have asymmetric effects on conditional variance. Negative shocks — bad news — typically amplify volatility more than positive shocks of the same magnitude, a stylised fact known as the leverage effect. TGARCH captures this asymmetry through a threshold indicator that switches on when the previous period's shock was negative.	The Exponential GARCH (EGARCH) model, introduced by Nelson (1991), extends the standard GARCH framework by modelling the logarithm of conditional variance. This ensures variance is always positive without parameter constraints and, crucially, allows negative and positive shocks to have asymmetric effects on volatility — capturing the well-known leverage effect in financial markets.