title: Measurement error in geometric morphometrics.
abstract: Geometric morphometrics-a set of methods for the statistical analysis of shape once saluted as a revolutionary advancement in the analysis of morphology -is now mature and routinely used in ecology and evolution. However, a factor often disregarded in empirical studies is the presence and the extent of measurement error. This is potentially a very serious issue because random measurement error can inflate the amount of variance and, since many statistical analyses are based on the amount of "explained" relative to "residual" variance, can result in loss of statistical power. On the other hand, systematic bias can affect statistical analyses by biasing the results (i.e. variation due to bias is incorporated in the analysis and treated as biologically-meaningful variation). Here, I briefly review common sources of error in geometric morphometrics. I then review the most commonly used methods to measure and account for both random and non-random measurement error, providing a worked example using a real dataset.
authors.affiliation: Department of Biological, Geological and Environmental Sciences, University of Catania, via Androne 81, 95124, Catania, Italy. c.fruciano@unict.it.|School of Earth, Environmental and Biological Sciences, Queensland University of Technology, Brisbane, Queensland, 4000, Australia. c.fruciano@unict.it.
authors.forename: Carmelo
authors.initials: C
authors.lastname: Fruciano
mesh_terms: D000704:Analysis of Variance; D000715:Anatomy / Q000379:methods*; D001699:Biometry; D049628:Body Size; D012107:Research Design
keywords: Bias; Geometric morphometrics; Measurement error; Multivariate analysis