Table 2.

GEP models implemented for formulation of Ω₂.

	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	16	+	12	10	3	1.6537	1.5704	0.7334	0.7510
2	16	×	12	10	3	1.0423	7.2033	0.8943	0.4803
3	17	+	16	12	5	1.2837	2.9813	0.8495	0.5826
4	17	×	16	12	5	0.6100	2.7332	0.9634	0.3943
5	18	+	20	14	6	1.0736	1.6420	0.8987	0.7538
6	18	+	20	14	7	0.9494	2.3725	0.9114	0.6582
7	18	×	20	14	7	1.6790	2.0624	0.7379	0.6308
8	19	+	26	16	4	1.1151	2.2205	0.8835	0.5639
9	19	+	26	16	6	1.2882	1.7167	0.8369	0.7425
10	19	+	32	16	8	1.0141	4.0280	0.9022	0.5386
11	19	×	26	16	6	0.9926	3.2393	0.9234	0.4492
12	19	×	32	16	8	1.3855	1.7350	0.8096	0.7374
13	20	+	36	18	6	0.8760	0.9665	0.9152	0.9078
14	20	+	40	18	6	0.6549	0.6849	0.9618	0.9507
15	20	×	36	18	6	0.8287	1.1516	0.9256	0.9076
16	20	×	40	18	6	1.0576	0.7232	0.9093	0.9478
17	21	+	44	20	8	1.0122	0.8581	0.9009	0.9269
18	21	+	48	22	8	0.7930	0.8737	0.9312	0.9375
19	21	×	48	22	8	0.9149	1.2908	0.9468	0.8372
20	22	+	40	18	6	0.6948	0.7106	0.9479	0.9499
21	22	+	44	20	8	0.8947	1.7590	0.9107	0.7040
22	22	×	44	20	8	1.0840	1.6828	0.8133	0.6727
23	23	+	40	18	6	1.1041	1.8122	0.8633	0.6846
24	23	×	40	18	6	1.4955	1.9729	0.7415	0.6232
25	24	+	40	18	6	1.9677	2.1566	0.6434	0.5638