Source

S (sum of squares)

Φ (DF)

Ψ (mean square)

χ (F value)

τ (Prob. > F)

Model

2.332E+005

10

23,318.34

13.23

<0.0001

X₁-collector dose

21,675.00

1

21,675.00

12.30

0.0025

X₂-pH

1200.00

1

1200.00

0.68

0.4201

X₃-flotation speed

33.33

1

33.33

0.019

0.8921

X₄-air flow rate

12,675.00

1

12,675.00

7.19

0.0152

X₂X₄

21,025.00

1

21,025.00

11.93

0.0028

X₃X₄

625.00

1

625.00

0.35

0.5589

$X_1^2$

1.206E+005

1

1.206E+005

68.42

<0.0001

$X_2^2$

36,567.61

1

36,567.61

20.75

0.0002

$X_3^2$

11,762.21

1

11,762.21

6.67

0.0187

$X_4^2$

76,830.45

1

76,830.45

43.60

<0.0001

Residual

31,720.00

18

1762.22

Lack of Fit

28,800.00

14

2057.14

2.82

0.1636