Parameter

Model term

Estimated regression coefficient

F-ratio

p-value

β₀

Intercept

−147.943

24.501

0.001

Linear

β₁

x₁

-

-

0.240^a

β₂

x₂

2.206

28.621

0.002

β₃

x₃

4.965

50.833

0.003

β₄

x₄

39.264

54.614

0.001

Quadratic

β₁₁

x₁ * x₁

-

-

0.800^a

β₂₂

x₂ * x₂

−0.007

24.010

0.002

β₃₃

x₃ * x₃

-

-

0.310^a

β₄₄

x₄ * x₄

15.363

18.042

0.001

Interaction

β₁₂

x₁ * x₂

-

-

0.093^a

β₁₃

x₁ * x₃

-

-

0.351^a

β₁₄

x₁ * x₄

-

-

0.272^a

β₂₃

x₂ * x₃

-

-

0.101^a

β₂₄

x₂ * x₄

-

-

0.210^a

β₃₄

x₃ * x₄

-

-

0.282^a

R²

-

0.888

-

-

Regression (F-ratio, p-value)

-

-

34.771

0.003