Characterization and Optimization of Calcination Process Parameters for Extraction of Aluminum from Ethiopian Kaolinite

Table 6

Summary of lack of fit and statistical analysis in model selection for extracted aluminum.

Source	Sequential value	Lack of fit value	Adj. R^2	Pred. R^2
Linear	0.0012	<0.0001	0.5478	0.4469
2 FI	0.9422	<0.0001	0.4593	0.0078
Quadratic	<0.0001	0.3889	0.9986	0.9965
Cubic (cubic model was aliased conversion for extracted aluminum)	0.3889		0.9988