highly significantP <0.01
The coefficients ( X 1 , X 2 , X 3 ) and quadratic term coefficient ( X 2 2 ) were highly significant ( P <0.01); moreover, the interaction term coefficient ( X 2 X 3 ) was significant ( P <0.05).
The coefficients ( X 1 , X 2 , X 3 ) and quadratic term coefficient ( X 2 2 ) were highly significant ( P <0.01); moreover, the interaction term coefficient ( X 2 X 3 ) was significant ( P <0.05).