Table 2.

ANOVA results for the studied factors

Source	PS					PDI						ZP
	Sum of squares	df	Mean square	F value	p-value prob > F	Sum of squares		df	Mean square	F value	p-value prob > F	Sum of squares	df	Mean square	F value	p-value prob > F
Order	Quadratic					Quadratic						Quadratic
Model	47303.8	5	9460.8	68.2	< 0.0001	0.11		5	0.021	17.1	0.0008	518.34	5	103.67	65.29	< 0.0001
X1—PC:VA	3672.8	1	3672.8	26.5	0.0013	0.019		1	0.019	15.6	0.0055	367.75	1	367.75	231.61	< 0.0001
X2—Prec.conc	89.4	1	89.39	0.6	0.4485	4.2E − 003		1	4.225E − 003	3.4	0.1068	48.40	1	48.40	30.48	0.0009
X12	0.5	1	0.49	3.5E − 003	0.9543	1.3E − 017		1	1.3E − 017	1.2E − 014	1.0000	0.016	1	0.016	9.8E − 003	0.9238
X12	25257.9	1	25257.9	182.1	< 0.0001	0.025		1	0.025	19.9	0.0029	3.20	1	3.20	2.01	0.1987
X22	12843.9	1	12843.9	92.6	< 0.0001	0.047		1	0.047	38.3	0.0004	101.94	1	101.94	64.20	< 0.0001
Residual	970.8	7	138.7			8.6E − 003		7	1.2E − 003			11.11	7	1.59
Lack of fit	760.8	3	253.6	4.8	0.0811	6.1E − 003		3	2.0E − 003	3.2	0.1483	8.23	3	2.74	3.81	0.1144
Pure error	209.9	4	52.5			2.6E − 003		4	6.4E − 004			2.88	4	0.72
Cor total	48274.6	12				8.6E − 003		7	1.2E − 003			529.45	12
R2		0.9799				0.9244						0.9790
Adjusted R2		0.9655				0.8705						0.9640
Predicted R2		0.8811				0.6873						0.8809
Adequate precision		30.183				16.164						25.747