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Garch Model

The Generalized Autoregressive Conditional Heteroskedasticity (GARCH) model is a statistical tool used primarily in financial econometrics to analyze and forecast the volatility of time series data. It extends the Autoregressive Conditional Heteroskedasticity (ARCH) model proposed by Engle in 1982, allowing for a more flexible representation of volatility clustering, which is a common phenomenon in financial markets. In a GARCH model, the current variance is modeled as a function of past squared returns and past variances, represented mathematically as:

σt2=α0+∑i=1qαiϵt−i2+∑j=1pβjσt−j2\sigma_t^2 = \alpha_0 + \sum_{i=1}^{q} \alpha_i \epsilon_{t-i}^2 + \sum_{j=1}^{p} \beta_j \sigma_{t-j}^2σt2​=α0​+i=1∑q​αi​ϵt−i2​+j=1∑p​βj​σt−j2​

where σt2\sigma_t^2σt2​ is the conditional variance, ϵ\epsilonϵ represents the error terms, and α\alphaα and β\betaβ are parameters that need to be estimated. This model is particularly useful for risk management and option pricing as it provides insights into how volatility evolves over time, allowing analysts to make better-informed decisions. By capturing the dynamics of volatility, GARCH models help in understanding the underlying market behavior and improving the accuracy of financial forecasts.

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