Table 2.
The Box-Behnken design for the RSM

Run	Independent variables (coded)			Independent variables (actual)
	X1	X2	X3	X1	X2	X3
	1	1	0	-1	90	70	30
2	0	0	0	80	70	60
3	1	0	1	90	70	90
4	-1	1	0	70	80	60
5	0	0	0	80	70	60
6	0	-1	-1	80	60	30
7	-1	0	-1	70	70	30
8	1	-1	0	90	60	60
9	-1	0	1	70	70	90
10	0	-1	1	80	60	90
11	1	1	0	90	80	60
12	0	1	1	80	80	90
13	0	0	0	80	70	60
14	0	0	0	80	70	60
15	-1	-1	0	70	60	60
16	0	1	-1	80	80	30
17	0	0	0	80	70	60
	Independent variables			Levels
				-1	0	1
	X1, Ethanol concentration (%)			70	80	90
	X2, Extraction temperature (°C)			60	70	80
	X3, Extraction time (min)			30	60	90