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Statistica Sinica 33 (2023), 331-351

ON THE CONSISTENCY OF LEAST SQUARES ESTIMATOR
IN MODELS SAMPLED AT RANDOM TIMES DRIVEN
BY LONG MEMORY NOISE: THE JITTERED CASE

Héctor Araya1, Natalia Bahamonde2, Lisandro Fermín3, Tania Roa1 and Soledad Torres3

1Universidad Adolfo Ibáñez, 2Pontificia Universidad Católica de Valparaíso and 3Universidad de Valparaíso

Abstract: In numerous applications, data are observed at random times. Our main purpose is to study a model observed at random times that incorporates a long-memory noise process with a fractional Brownian Hurst exponent H. We propose a least squares estimator in a linear regression model with long-memory noise and a random sampling time called "jittered sampling". Specifically, there is a fixed sampling rate 1/N, contaminated by an additive noise (the jitter) and governed by a probability density function supported in [0, 1/N]. The strong consistency of the estimator is established, with a convergence rate depending on N and the Hurst exponent. A Monte Carlo analysis supports the relevance of the theory and produces additional insights, with several levels of long-range dependence (varying the Hurst index) and two different jitter densities.

Key words and phrases: Least squares estimator, long-memory noise, random times, regression model.

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