Table 3.

GEP models implemented for formulation of Ω₄.

	GEP parameters					Results
No.	No. of test datasets	Linking function	No. of chromosomes	Head size	Genes' number	RMSE for train datasets	RMSE for test datasets	R2 for train datasets	R2 for test datasets
1	19	+	25	12	3	0.7013	0.5976	0.8368	0.7524
2	19	+	30	12	3	0.4235	0.5940	0.9422	0.7829
3	19	×	30	12	3	0.4214	0.6268	0.9409	0.7384
4	20	+	35	13	5	0.3754	0.4733	0.9551	0.8799
5	20	×	35	13	5	0.4765	0.4854	0.9311	0.7762
6	20	+	40	18	6	0.4127	0.3867	0.9400	0.9106
7	20	×	40	18	6	0.4424	0.3332	0.9410	0.8974
8	21	+	40	15	8	0.2987	0.3149	0.9722	0.9274
9	21	×	40	18	8	0.4016	0.7037	0.9029	0.8937
10	21	+	40	16	8	0.2594	0.4838	0.9466	0.8854
11	21	×	40	16	8	0.3291	0.5355	0.9363	0.9121
12	22	+	41	15	8	0.3785	0.5857	0.9098	0.7240
13	22	+	42	15	8	0.3390	0.5075	0.9380	0.8097
14	22	+	43	15	9	0.3328	0.5275	0.9324	0.7886
15	22	×	43	15	9	0.3780	0.4736	0.9028	0.8875
16	23	+	44	15	8	0.3687	0.4194	0.8760	0.8888
17	23	×	44	15	8	0.3081	0.5025	0.9007	0.8217
18	23	+	45	16	9	0.4271	0.3242	0.8462	0.8869
19	23	×	45	16	9	0.3756	0.4332	0.8958	0.8129
20	24	+	40	18	8	0.4144	0.3766	0.8710	0.8160
21	24	×	40	18	8	0.3288	0.5072	0.9079	0.7888
22	24	+	40	20	10	0.7568	1.0106	0.6791	0.7755
23	24	×	40	20	10	0.3622	0.5174	0.8937	0.8546
24	25	+	40	22	10	0.3697	0.5136	0.9172	0.7028
25	25	×	40	22	10	0.3509	0.3115	0.9114	0.8837