Table 2.

Experimental trials derived from Design-Expert Software.

RUN	Independent Variables
	Coded Values			Actual Values
	X1	X2	X3	X1	X2	X3
1	0	+1	−1	6	9	24
2	0	0	0	6	6	48 *
3	0	−1	−1	6	3	24
4	0	0	0	6	6	48 *
5	0	+1	+1	6	9	72
6	+1	−1	0	9	3	48
7	0	0	0	6	6	48 *
8	0	−1	+1	6	3	72
9	−1	+1	0	3	9	48
10	+1	0	+1	9	6	72
11	0	0	0	6	6	48 *
12	−1	−1	0	3	3	48
13	−1	0	+1	3	6	72
14	−1	0	−1	3	6	24
15	0	0	0	6	6	48 *
16	+1	+1	0	9	9	48
17	+1	0	−1	9	6	24

(* replication of middle level = 0:0:0).