Variable

Coef.

Std. Err.

t

P > |t|

${\beta }_{Pi}$

0.5561827

0.2002771

2.7770654

0.220

${\beta }_{Pi}^2$

−0.2511102

0.0892295

−2.8142051

0.217

Constant

−0.3014719

0.1114963

−2.7038749

0.226

R-squared

0.951

Adj R-squared

0.855