Table 3.

Analysis of variance for regression model.

Source of Variance	Sum of squares	Degree of freedom	Mean square	F	Pr>F	Significance
Model	3.03	9	0.34	254.35	<0.0001	**
X1	1.63	1	1.63	1231.02	<0.0001	**
X2	0.092	1	0.092	69.29	0.0004	**
X3	0.41	1	0.41	307.07	<0.0001	**
X1X2	1.09E-03	1	1.09E-03	0.82	0.4057
X1X3	0.011	1	0.011	8.18	0.0354	*
X2X3	1.00E-06	1	1.00E-06	7.57E-04	0.9791
X12	0.72	1	0.72	544.69	<0.0001	**
X22	0.049	1	0.049	37.32	0.0017	**
X32	0.21	1	0.21	156.35	<0.0001	**
Residual	6.61E-03	5	1.32E-03
Lack of Fit	6.04E-03	3	2.02E-03	7.14	0.1254
Pure error	5.65E-03	2	2.82E-04
Total	3.03	14

Note: R² = 0.9978, Adj R² = 0.9939, Pred R² = 0.9677, **p < 0.01 is extremely significant; *p < 0.05 significant. X₁ = CaCl₂, X₂ = Urea, X₃ = Temperature.