Table 4. The processes of binary search for the optimal subset features .

Iteration	Number of features	Pearson Correlation Coefficient
1	275	0.670
2	275/2 = 137	0.682
3	137/2 = 68	0.691
4	68/2 = 34	0.684
5	34 + (68–34)/2 = 51	0.688
6	51 + (68–51)/2 = 59	0.687
7	59 + (68–59)/2 = 63	0.685
8	63 + (68–63)/2 = 65	0.684
9	65 + (68–65)/2 = 66	0.687