Table 6.

Significance of quadratic model coefficients for DPA production.

Factor	Coefficient values	F-values	p-value
Intercept	341.2	115.35	<0.0001
x1	47.0	69.50	<0.0001
x2	119.6	5.59	0.0501
x3	225.5	16.99	0.0045
${\text{x}}_1^2$	−2.66	1.09	0.3309
${\text{x}}_2^2$	−13.1	8.68	0.0215
${\text{x}}_3^2$	−97.1	6.64	0.0367
x1x2	0.37	363.08	<0.0001
x1x3	2.83	225.96	<0.0001
x2x3	−6.16	244.14	<0.0001