Table 4. Analysis of variance for the third-order model

Model terms: X1, X2, X3; X12, X22, X32; X1X2, X1X3, X2X3; X13, X23, X33; X1X2X3
Source	Degrees of freedom	Sum of squares	Mean square	F-value	p-value
Model	13	1334.9522	102.6886	2.34	0.2627
Error	3	131.4045	43.8015	-	-
Total	16	1466.3568	-	-	-
Root MSE = 6.6183		R-square = 0.9104		Adjusted R-square = 0.5221
Test of lack of fit
Source	Degrees of freedom	Sum of squares	Mean square	F-value	p-value
Lack of fit	1	125.4391	125.4391	42.06	0.0230
Pure Error	2	5.9654	2.9827	-	-