Table 6.

Error Metrics for calcium interpolation methods, generated via leave-one-out cross-validation.

Method	r	RMSE	MAE	MBE	MSA
NN	0.78	32.77	13.25	0.09	0.21
IDW-OR	0.82	28.03	12.25	0.16	0.23
IDW-OM	0.82	28.63	12.09	0.13	0.21
OK	0.82	28.61	13.39	−0.01	0.30
OK-ZN	0.84	27.06	11.79	0.01	0.22

The best interpolation methods for each metric are highlighted in bold. Metrics: r = correlation coefficient, RMSE = Root Mean Square Error, MAE = Mean Absolute Error, MBE = Mean Bias Error, MSA = Median Symmetric Accuracy. Methods: NN = nearest neighbour; IDW-OR = inverse distance weighting, RMSE-optimised; IDW-OM = inverse distance weighting, MAE-optimised; OK = ordinary kriging, unconstrained nugget; OK-ZN = ordinary kriging, zero nugget.