Table 3.
Analysis of variance showing effects of treatment variables as linear or quadratic terms and interaction effects on response variables of classification ratio

Source	Degree of freedom	Fine fraction		Coarse fraction
		F value	Prov>F	F value	Prov>F
		Model	9	19.22	<0.0001	19.39	<0.0001
Liner	3	49.94	<0.0001	50.32	<0.0001
Quadratic	3	5.32	0.0091	5.41	0.0085
Cross	3	2.41	0.1027	2.45	0.0984
R2		0.911		0.911
X11)	4	27.18	<0.0001	27.42	<0.0001
X2 2)	4	7.38	0.0012	7.43	0.0012
X3 3)	4	10.50	0.0002	10.63	0.0002

X₁: Mill grinding speed (rpm)
X₂: Separate reverse wheel speed (rpm)
X₃: Air classification reverse wheel speed (rpm)