Model derivation: final plot of residual error (modeled minus measured FA) versus patient covariates. A = age, B = height, and C = weight. There was no (linear) correlation with age (r2 = 0.00), height (r2 = 0.01 after implementing it as a covariate in the model) and weight (r2 = 0.00).
Hendrickx et al. BMC Anesthesiology 2011 11:13 doi:10.1186/1471-2253-11-13