Table 3.

Regression summaries and analysis of variance.

Variables	Tensile Strength (MPa)	Elongation at Break (%)	Water Absorption (%)
Model	Quadratic	Quadratic	Quadratic
Intercept	15.83 **	13.00 **	31.17 **
X1	−0.55 **	−1.88 **	4.76 **
X2	−2.03 **	−1.61 **	2.86 **
X3	0.40 **	0.36 *	0.21
X1X2	−0.12 *	−0.28	−2.82 **
X1X3	−0.23 **	0.23	−0.40
X2X3	0.17 *	−0.65 **	0.49
X12	0.07	−0.03	−2.40 *
X22	0.07	−1.85 **	−1.34
X32	0.22 **	−0.75 **	−0.33
F-value (model)	562.01 **	96.26 **	22.02 **
CV%	0.53	2.38	4.29
R2	0.999	0.994	0.975
Adjusted R2	0.997	0.984	0.931
Adeq. Precision	73.655	30.886	16.555
Lack-of-fit(p-value) ψ	0.259	0.077	0.221

* Indicates significant difference (p < 0.05). ** Indicates most significant difference (p < 0.01). ^ψ Selected model exhibits insignificant lack-of-fit (p > 0.05). X₁: tapioca starch content (%); X₂: maleic anhydride content (%); X₃: screw speed (rpm).