Fig. 4

Distribution (95% confidence intervals) of calibration and validation statistics from 100 simulations of models predicting WBD (g/cm³) in the 90° angles and mixed angle model of multiple tree species using four different variable selection methods on NIR spectra. Each model permutation included 80% of the data for internal calibration and the remaining 20% for validation. The black vertical line represents median value; the orange colour box represents the Rep variable selection methods