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Elsevier, Journal of Neuroscience Methods, 1(142), p. 17-26, 2005

DOI: 10.1016/j.jneumeth.2004.07.008

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Trimmed estimators for robust averaging of event-related potentials

Journal article published in 2005 by Zbigniew Leonowicz ORCID, Juha Karvanen ORCID, Sergei L. Shishkin
This paper is available in a repository.
This paper is available in a repository.

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Abstract

Averaging (in statistical terms, estimation of the location of data) is one of the most commonly used procedures in neuroscience and the basic procedure for obtaining event-related potentials (ERP). Only the arithmetic mean is routinely used in the current practice of ERP research, though its sensitivity to outliers is well- known. Weighted averaging is sometimes used as a more robust procedure, however, it can be not sufficiently appropriate when the signal is nonstationary within a trial. Trimmed estimators provide an alternative way to average data. In this paper, a number of such location estimators (trimmed mean, Winsorized mean and recently introduced trimmed L{mean) are reviewed, as well as arithmetic mean and median. A new robust location estimator tanh, which allows the data{dependent optimization, is proposed for averaging of small number of trials. The possibilities to improve signal-to-noise ratio (SNR) of averaged waveforms using trimmed location estimators are demonstrated for epochs randomly drawn from a set of real auditory evoked potential data.