Journal of Financial Econometrics Advance Access originally published online on August 23, 2006
Journal of Financial Econometrics 2006 4(4):617-635; doi:10.1093/jjfinec/nbl002
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Sample and Implied Volatility in GARCH Models
University of Utah
Utah State University
ardas Zitikis
University of Western Ontario
Address correspondence to Piotr Kokoszka, Department of Mathematics and Statistics, Utah State University, 3900 Old Main Hill, Logan, UT 84322-3900, or e-mail: piotr.kokoszka{at}usu.edu.
The unconditional variance of various GARCH-type models is a function h(
) of the parameter vector
which is estimated by
. For most models used in practice, closed-form expressions of h(·) have been found. On the contrary, the unconditional variance can be estimated by the sample variance
2. This article establishes the asymptotic distributions of the differences
2 h(
) and
2 h(
) for broad classes of GARCH-type models. Even though both limit distributions are normal, the asymptotic variances are not equal. Potential practical consequences of these results are discussed.
KEYWORDS: GARCH processes, statistical hypothesis test, volatility
Received July 12, 2005; revised July 17, 2006; accepted July 20, 2006