Synonyms
Definition
An outlier is an extreme sample distant from the majority of other samples (Grubbs 1969). In lipidomics, this represents a sample where one or more lipid measures are distant from the other samples such that the lipid profile as a whole can be considered an outlier.
Introduction
An outlier pattern for a given sample could be a result of either the inherent characteristics of the sample (representing biological diversity) or technical error in the measurements. In lipidomics studies, such technical variation may arise from incorrect handling of the sample (including transportation, centrifugation, extraction procedures, addition of internal standards, mass spectrometry analysis, and many other processes).
Such data quality issues must be addressed prior to performing any advanced statistical analysis. A small proportion of unchecked technical outliers in a given dataset have the potential to bias the statistical parameter estimation,...
References
Grubbs FE. Procedures for detecting outlying observations in samples. Technometrics. 1969;11(1):1–21.
Hodge VJ, Austin J. A survey of outlier detection methodologies. Artif Intell Rev. 2004;22:85–126.
Rousseeuw PJ, Leroy AM. Robust regression and outlier detection. New York: Wiley; 1996.
Zimek A, Schubert E, Kriegel H-P. A survey on unsupervised outlier detection in high-dimensional numerical data. Stat Anal Data min. 2012;5(5):363–87.
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Mundra, P.A., Huynh, K., Meikle, P.J. (2015). Sample Handling and Automation: Outlier. In: Wenk, M. (eds) Encyclopedia of Lipidomics. Springer, Dordrecht. https://doi.org/10.1007/978-94-007-7864-1_56-1
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DOI: https://doi.org/10.1007/978-94-007-7864-1_56-1
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