Table 2.

The results of analysis of variance (ANOVA) of the response surface quadratic model.

Source	Coefficient Estimate	Sum of Squares	df	Mean Square	F-value	p-value	Significance
Model	N/A	301.02	14	21.50	25.91	<0.0001	**
Intercept	11.31	N/A	N/A	N/A	N/A	N/A	N/A
X1: Pressure	2.25	60.98	1	60.98	73.49	<0.0001	**
X2: Flow	1.97	46.77	1	46.77	56.36	<0.0001	**
X3: Temperature	0.007	0.0005	1	0.0005	0.0006	0.9802	not significant
X4: Time	3.50	146.72	1	146.72	176.82	<0.0001	**
X1 X2	−1.20	5.76	1	5.76	6.94	0.0218	*
X1X3	1.67	11.09	1	11.09	13.36	0.0033	**
X1X4	−0.81	2.64	1	2.64	3.18	0.0997	not significant
X2X3	−0.38	0.59	1	0.59	0.71	0.4174	not significant
X2X4	−1.18	5.57	1	5.57	6.71	0.0236	*
X3X4	0.38	0.57	1	0.57	0.69	0.4234	not significant
X12	−1.04	5.76	1	5.76	6.94	0.0218	*
X22	−1.10	6.47	1	6.47	7.80	0.0163	*
X32	−1.20	7.62	1	7.62	9.19	0.0105	*
X42	−1.79	17.05	1	17.05	20.55	0.0007	**
Residual	N/A	9.96	12	0.83	N/A	N/A	N/A
Lack of Fit	N/A	9.69	10	0.97	7.38	0.1252	not significant
Pure Error	N/A	0.26	2	0.13	N/A	N/A	N/A
Cor Total	N/A	310.98	26	N/A	N/A	N/A	N/A
R2 = 0.9680		Adjusted R2 = 0.9306		Predicted R2 = 0.8185		Adeq Precision = 17.1612

X₁, X₂, X₃, and X₄ are the codes of pressure, flow, temperature, and time in the BBD model, respectively. df: degree of freedom. N/A: Not applicable. * p < 0.05, ** p < 0.01.