Table 4.

GEP models implemented for formulation of Ω₆.

	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	17	+	12	10	6	0.7214	0.7639	0.7316	0.6161
2	17	×	12	10	6	0.7441	0.7421	0.7648	0.6434
3	18	+	15	12	8	0.6841	0.6517	0.7666	0.7074
4	18	×	15	12	8	0.5303	0.4811	0.8629	0.7512
5	19	+	20	14	8	0.8995	0.7311	0.6500	0.7092
6	19	×	20	14	8	0.7740	0.6840	0.7486	0.6618
7	20	+	20	18	6	0.5048	0.9539	0.8707	0.8019
8	20	+	30	14	8	0.5362	0.7348	0.7746	0.6956
9	20	×	40	18	6	0.4899	0.4570	0.8402	0.8592
10	21	+	35	14	6	0.4706	0.4207	0.8241	0.8270
11	21	+	40	15	8	0.4815	0.8040	0.8308	0.8258
12	22	+	40	16	8	0.4936	0.4143	0.8684	0.8605
13	22	×	40	16	8	0.4466	0.5530	0.8903	0.8600
14	23	+	45	18	6	0.4323	0.4032	0.8915	0.8672
15	23	+	45	20	8	0.4259	0.5834	0.8375	0.8335
16	24	+	45	22	10	0.3558	0.3287	0.9174	0.8979
17	25	×	45	22	12	0.3158	0.5763	0.9208	0.9158
18	19	+	30	10	12	0.2356	0.2042	0.9686	0.9473
19	19	+	35	10	12	0.2124	0.3387	0.9618	0.9080
20	19	×	40	10	12	0.4145	0.3464	0.8674	0.9139
21	20	+	40	12	12	0.3221	0.6439	0.9097	0.9119
22	20	+	45	10	12	0.4234	0.3975	0.8918	0.9079
23	20	×	45	12	12	0.4262	0.4905	0.8786	0.8983
24	21	+	30	12	14	0.6265	0.7527	0.8515	0.8249
25	21	+	30	14	14	0.7688	0.3642	0.8756	0.8844