Coupling a Bat Algorithm with XGBoost to Estimate Reference Evapotranspiration in the Arid and Semiarid Regions of China

Table 4

Results of the statistical indicators for all models in the Datong station during the training and testing stages.

Model	Training					Testing
	R^2	RMSE	MAE	RMSEmax10%	MAEmax10%	R^2	RMSE	MAE	RMSEmax10%	MAEmax10%
GPR1	0.841	0.66	0.519	1.392	1.373	0.832	0.695	0.559	1.333	1.328
GPR2	0.978	0.258	0.196	0.586	0.563	0.972	0.372	0.302	0.744	0.738
GPR3	0.98	0.242	0.181	0.565	0.547	0.956	0.444	0.35	0.898	0.891
GPR4	0.974	0.279	0.202	0.673	0.645	0.978	0.297	0.221	0.668	0.664
GPR5	0.988	0.197	0.138	0.483	0.46	0.951	0.398	0.251	1.089	1.019
GPR6	0.986	0.209	0.139	0.548	0.517	0.958	0.37	0.25	0.919	0.877
MARS1	0.964	0.315	0.236	0.723	0.71	0.97	0.292	0.227	0.649	0.631
MARS2	0.986	0.199	0.15	0.465	0.453	0.962	0.421	0.337	0.821	0.812
MARS3	0.984	0.209	0.157	0.481	0.468	0.953	0.512	0.379	1.158	1.148
MARS4	0.99	0.162	0.121	0.371	0.363	0.98	0.271	0.216	0.559	0.552
MARS5	0.992	0.154	0.11	0.377	0.362	0.992	0.153	0.12	0.321	0.32
MARS6	0.994	0.122	0.087	0.3	0.292	0.992	0.189	0.121	0.509	0.483
BAXGB1	0.978	0.238	0.179	0.541	0.531	0.972	0.291	0.23	0.592	0.587
BAXGB2	0.988	0.209	0.148	0.518	0.505	0.974	0.284	0.227	0.576	0.568
BAXGB3	0.998	0.076	0.057	0.175	0.168	0.955	0.438	0.311	1.067	1.057
BAXGB4	0.996	0.092	0.069	0.214	0.207	0.988	0.191	0.153	0.403	0.398
BAXGB5	0.996	0.108	0.076	0.266	0.255	0.992	0.146	0.112	0.337	0.328
BAXGB6	1	0.03	0.022	0.068	0.066	0.996	0.116	0.087	0.272	0.258

Note. Bold font indicates the best model.