Table 5. Statistical Evaluation Results of the Sulfur Solubility Prediction Model (a, b).

data sets	AARD (%)	SD	RMSE	R2
(a) WOA-WLSSVM
training sets	3.35	0.06	0.03	0.9991
testing sets	3.68	0.07	0.04	0.9985
checking sets	3.87	0.09	0.01	0.9896
all sets	3.45	0.07	0.02	0.9987
(b) GWO-WLSSVM
training sets	3.43	0.06	0.03	0.9987
testing sets	3.84	0.08	0.05	0.9983
checking sets	3.89	0.08	0.01	0.9888
all sets	3.47	0.07	0.02	0.9983