highly significantP < 0.01
The linear coefficients of X 1 , X 2 and X 3 , cross-product coefficient of X 1 X 3, and quadratic coefficients of X 1 2 , X 2 2 and X 3 2 were highly significant ( P < 0.01).
The linear coefficients of X 1 , X 2 and X 3 , cross-product coefficient of X 1 X 3, and quadratic coefficients of X 1 2 , X 2 2 and X 3 2 were highly significant ( P < 0.01).