Name

Coefficient

Standard Error

T calculated

p-value

Before

After

Before

After

Before

After

Before

After

Average

142.16

149.47

5.64

4.69

25.20

31.88

0.0000

0.0000

$x_1$

24.31

24.31

3.46

3.95

7.04

6.15

0.0009

0.0005

$x_1^2$

−15.97

−18.25

4.11

4.49

−3.88

−4.07

0.0116

0.0048

$x_2$

−46.93

−46.93

3.46

3.95

−13.58

−11.89

0.0000

0.0000

$x_2^2$

7.76

-

4.11

-

1.89

-

0.1177

-

$x_1-x_2$

3.69

-

4.89

-

0.75

-

0.4844

-