Table 2.

The optimization of the original model of Equation 1 for production of butyric acid as calculated from results of gas chromatography analysis using the probability factors f. x₁ is the type of monomer used, x₂ is the vinylazlactone monomer grafting time, and x₃ is the lipase immobilization time; p_i are the regression coefficients of Equation 1, R is the correlation coefficient.

	f, probability factors
	step 1	step 2	step 3	step 4	step 5	step 6	step 7
constant	0.820	0.730	0.720	-	-	-	-
x1	0.744	0.718	0.695	0.677	-	-	-
x2	0.706	0.674	0.652	0.294	0.269	-	-
x3	0.643	0.090	0.065	0.001	0.001	0.000	0.000
x1·x2	0.055	0.034	0.022	0.014	0.002	0.002	0.002
x1·x3	0.299	0.252	0.213	0.185	0.107	0.110	-
x2·x3	0.045	0.027	0.017	0.001	0.001	0.000	0.001
x12	0.927	0.916	-	-	-	-	-
x22	0.144	0.106	0.078	0.061	0.049	0.000	0.000
x32	0.967	-	-	-	-	-	-
	pi, regression coefficients
	step 1	step 2	step 3	step 4	step 5	step 6	step 7
p0	3.91	3.35	3.13	-	-	-	-
p1	3.00	3.00	3.00	3.00	-	-	-
p2	0.53	0.54	0.53	0.83	0.83	-	-
p3	3.17	3.44	3.44	3.94	3.94	4.38	4.38
p4	1.16	1.16	1.16	1.16	1.25	1.25	0.86
p5	-1.67	-1.67	-1.67	-1.67	-1.30	-1.30	-
p6	-0.40	-0.40	-0.40	-0.44	-0.44	-0.44	-0.44
p7	-0.45	-0.46	-	-	-	-	-
p8	0.09	0.09	0.09	0.08	0.08	0.12	0.12
p9	0.03	-	-	-	-	-	-
R	0.8445	0.8444	0.8441	0.841	0.8373	0.8122	0.7545