Table 2.

ANOVA of the responses and model fit statistics for regression models.

Source	Sum of squares	DF	Mean square	F-value	p-value
Model	35.39	14	2.53	19.28	<0.0001
X1	1.52	1	1.52	11.59	0.0043
X2	8.35	1	8.35	63.69	<0.0001
X3	0.0019	1	0.0019	0.0143	0.9065
X4	0.304	1	0.304	2.32	0.1501
X1X2	1.09	1	1.09	8.33	0.012
X1X3	0.0025	1	0.0025	0.0191	0.8921
X1X4	0.0036	1	0.0036	0.0275	0.8708
X2X3	0.0001	1	0.0001	0.0008	0.9784
X2X4	0.2025	1	0.2025	1.54	0.2343
X3X4	1.27	1	1.27	9.65	0.0077
X12	7.71	1	7.71	58.79	<0.0001
X22	15.49	1	15.49	118.12	<0.0001
X32	2.13	1	2.13	16.22	0.0012
X42	7.32	1	7.32	55.87	<0.0001
Residual	1.84	14	0.1311
Lack of fit	1.54	10	0.1544	2.12	0.2447
Pure error	0.2917	4	0.0729
Cor Total	37.23	28
R2	0.9507
Adj R2	0.9014
Pred R2	0.7489
CV%	3.17

X₁, X₂, X₃ and X₄ represent the same as above.