Table 2.

Full factorial central composite design matrix for biodiesel production

Run	Independent variables			Reponses (BD-100)		Reponses (BD-190)		Reponses (BD-240)
	A: Methanol/oil ratio	B: Catalyst concentration (wt%)	C: Reaction time (min)	Actual yield (%)	Predicted yield (%)	Actual yield (%)	Predicted yield (%)	Actual yield (%)	Predicted yield (%)
1	− 1 (6.00)	− 1 (1.00)	− 1 (60.00)	89.53	88.98	91.3	87.68	98.04	92.17
2	+ 1 (12.00)	− 1 (1.00)	− 1(60.00)	96.47	98	96.7	98.24	98.73	96.93
3	− 1 (6.000)	+ 1 (2.00)	− 1 (60.00)	79.75	78.42	72.96	69.95	89.39	89.11
4	+ 1 (12.00)	+ 1 (2.00)	− 1 (60.00)	84.33	86.99	87.39	81.5	94.38	93.87
5	− 1 (6.00)	− 1 (1.00)	+ 1 (100.00)	94.91	92.82	86.52	87.75	79.06	88.81
6	+ 1 (12.00)	− 1 (1.00)	+ 1 (100.00)	94.83	96.73	92.67	91.01	97.41	93.57
7	− 1 (6.00)	+ 1 (2.00)	+ 1 (100.00)	76.14	75.18	81.63	75.42	87.41	85.75
8	+ 1 (12.00)	+ 1 (2.00)	+ 1 (100.00)	77.51	78.64	80.71	79.67	89.26	90.51
9	− α (3.00)	0 (1.50)	0 (80.00)	71.97	74.73	72.01	75.48	88.26	86.58
10	+ α (15.00)	0 (1.50)	0 (80.00)	90.53	87.21	89.09	90.29	94.35	96.1
11	0 (9.00)	− α (0.50)	0 (80.00)	96.29	96.28	95.45	93.22	96.47	94.4
12	0 (9.00)	+ α (3.00)	0 (80.00)	46.42	46.17	44.58	47.64	88.31	86.75
13	0 (9.00)	0 (1.50)	− α (30.00)	94.00	93.38	87.89	90.13	94.44	95.54
14	0 (9.00)	0 (1.50)	+ α (120.00)	88.93	89.32	85.93	87.09	93.6	87.98
15	0 (9.00)	0 (1.50)	0 (80.00)	93.94	93.38	84.55	86.07	94.62	91.34
16	0 (9.00)	0 (1.50)	0 (80.00)	92.22	93.38	83.69	86.07	83.21	91.34
17	0 (9.00)	0 (1.50)	0 (80.00)	94.31	93.38	85.6	86.07	92.25	91.34
18	0 (9.00)	0 (1.50)	0 (80.00)	93.1	93.38	83.92	86.07	91.67	91.34
19	0 (9.00)	0 (1.50)	0 (80.00)	93.92	93.38	84.25	86.07	89.45	91.34
20	0 (9.00)	0 (1.50)	0 (80.00)	89.53	88.98	84.67	86.07	85.79	91.34