Quantitative and stable limits of high-frequency statistics of Lévy processes: a Stein's method approach
Chiara Amorino, Arturo Jaramillo, Mark Podolskij
TL;DR
The paper develops a Stein's method framework to study high-frequency statistics of multidimensional Lévy processes and their convergence to mixed Gaussian limits. It proves a general stable-convergence criterion (Theorem ['stein']) to mixed normal limits, without embedding into a Gaussian space, and derives quantitative rates (Theorem ['th1']) for the convergence of the normalized statistic $Z^{(n)}$ to a Gaussian integral driven by a stochastic variance $A_t$. The results are organized around tail regimes indexed by $\alpha$ through hypotheses $m{H_1}(m{\alpha})$, with refined rates under stronger conditions ($\bm{H_2}$, $\bm{H_3}$). The methodology blends Stein's method with a $K$-function–style decomposition to handle stochastic variances and non-central limits, offering a general toolkit for stable limit theorems in non-Gaussian high-frequency settings and potential extensions to broader stochastic environments.
Abstract
We establish inequalities for assessing the distance between the distribution of errors of partially observed high-frequency statistics of multidimensional Lévy processes and that of a mixed Gaussian random variable. Furthermore, we provide a general result guaranteeing stable functional convergence. Our arguments rely on a suitable adaptation of the Stein's method perspective to the context of mixed Gaussian distributions, specifically tailored to the framework of high-frequency statistics.
