309
ENY-ARTICLE-2009-248
eng
AZ I07/2005/I-002
Leonowicz, Z
Wroclaw University of Technology, Poland
Trimmed estimators for robust averaging of event-related potentials
2005-01-18
10p
Journal of Neuroscience Methods, 2005, vol. 142, No. 1, pp. 17-26.
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.
averaging
event-related potentials
evoked potentials
mean
median
trimmed mean
robust estimators of location
trimmed estimators
Karvanen, J
Helsinki University of Technology, Finland
Shishkin, S L
Lomonosov State University, Russia
leon99@pwr.wroc.pl
http://zet10.ipee.pwr.wroc.pl/record/309/files/
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