Source of variation

Sum of squares

Degrees of freedom

Middle square

∑ Y_i²

18,256.86

11

1659.71

Because X₀

9628.53

1

9506.54

Because X₁

7799.50

1

8300.35

Because X₂

11.55

1

12.52

Because X₃

9.59

1

8.21

Because X₁₂

−25.36

1

14.47

Because X₁₃

122.58

1

15.57

Because X₂₃

259.01

1

244.38

Because X₁₂₃

147.22

1

147.22

Residual sum of squares

304.25

3

101.42

Mismatches

289.07

1

289.07

Experimental error

15.18

2

7.59