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Noise Induces Biased Estimation of the Correction Gain

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Authors
Ahn, Jooeun; Zhang, Zhaoran; Sternad, Dagmar
Issue Date
2016-07-27
Publisher
PUBLIC LIBRARY SCIENCE
Citation
PLOS ONE Vol.11 No.7, pp. e0158466
Keywords
Noise Induces Biased Estimation of the Correction Gain복합학
Abstract
The detection of an error in the motor output and the correction in the next movement are critical components of any form of motor learning. Accordingly, a variety of iterative learning models have assumed that a fraction of the error is adjusted in the next trial. This critical fraction, the correction gain, learning rate, or feedback gain, has been frequently estimated via least-square regression of the obtained data set. Such data contain not only the inevitable noise from motor execution, but also noise from measurement. It is generally assumed that this noise averages out with large data sets and does not affect the parameter estimation. This study demonstrates that this is not the case and that in the presence of noise the conventional estimate of the correction gain has a significant bias, even with the simplest model. Furthermore, this bias does not decrease with increasing length of the data set. This study reveals this limitation of current system identification methods and proposes a new method that overcomes this limitation. We derive an analytical form of the bias from a simple regression method (Yule-Walker) and develop an improved identification method. This bias is discussed as one of other examples for how the dynamics of noise can introduce significant distortions in data analysis.
ISSN
1932-6203
Language
English
URI
http://hdl.handle.net/10371/116911
DOI
https://doi.org/10.1371/journal. pone.0158466
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College of Education (사범대학)Dept. of Physical Education (체육교육과)Journal Papers (저널논문_체육교육과)
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