Table 3
Estimated coefficients of the fitted quadratic polynomial equation for different responses based on t-statistic

Parameter

Y (sphericity, %)

Coefficient

P value

Constant

97.80

0.000

  X 1

4.89

0.000

  X 2

1.51

0.018

  X 3

0.27

0.633

  X 4

−1.40

0.026

  X 1 X 1

−3.76

0.000

  X 2 X 2

−0.94

0.133

  X 3 X 3

−2.42

0.001

  X 4 X 4

−1.57

0.020

  X 1 X 2

−0.88

0.217

  X 1 X 3

0.01

0.993

  X 1 X 4

0.82

0.249

  X 2 X 3

0.33

0.633

  X 2 X 4

−0.63

0.369

  X 3 X 4

0.93

0.194