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Size correction in biology: how reliable are approaches based on (common) principal component analysis?

Berner, Daniel. (2011) Size correction in biology: how reliable are approaches based on (common) principal component analysis? Oecologia, Vol. 166, H. 4. pp. 961-971.

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Official URL: http://edoc.unibas.ch/dok/A6223549

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Abstract

Morphological traits typically scale with the overall body size of an organism. A meaningful comparison of trait values among individuals or populations that differ in size therefore requires size correction. A frequently applied size correction method involves subjecting the set of n morphological traits of interest to (common) principal component analysis [(C)PCA], and treating the first principal component [(C)PC1] as a latent size variable. The remaining variation (PC2–PCn) is considered size-independent and interpreted biologically. I here analyze simulated data and natural datasets to demonstrate that this (C)PCA-based size correction generates systematic statistical artifacts. Artifacts arise even when all traits are tightly correlated with overall size, and they are particularly strong when the magnitude of variance is heterogeneous among the traits, and when the traits under study are few. (C)PCA-based approaches are therefore inappropriate for size correction and should be abandoned in favor of methods using univariate general linear models with an adequate independent body size metric as covariate. As I demonstrate, (C)PC1 extracted from a subset of traits, not themselves subjected to size correction, can provide such a size metric.
Faculties and Departments:05 Faculty of Science > Departement Umweltwissenschaften > Zoologie > Evolutionary Biology (Salzburger)
UniBasel Contributors:Berner, Daniel
Item Type:Article, refereed
Article Subtype:Research Article
Bibsysno:Link to catalogue
Publisher:Springer
ISSN:0029-8549
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:27 Feb 2014 15:46
Deposited On:27 Feb 2014 15:46

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