Table 2.

Performance metrics of the six models evaluated during the derivation phase using bootstrap resampling procedure

Model	RMSE	MAE	R2
A	0.33	0.25	0.52
W	0.34	0.27	0.48
L	0.30	0.22	0.61
LA	0.30	0.22	0.61
LW	0.30	0.22	0.61
LWA	0.29	0.21	0.62

A – Age (in years) alone; W – Weight (in kg) alone; L – Length (in cm) alone; LA – Length and age; LW – Length and weight; LWA – Length, weight and age. RMSE – Residual mean square error; MAE – Mean absolute error; R² – Square of the Pearson correlation coefficient