Model Eq. (1) benchmarking residuals did not show
any trend with respect to any of the predictors. Average
residual is ÿ0.25 m (standard deviation3.6 m),
not signi®cantly different from zero. The mean of
absolute residuals is 3.1 m. The calibration model
Eq. (1) explains 57% of the variability of the benchmarking
data set.