marginally significantp < 0.1
Given η has a significant or marginally significant ( p < 0.1) relationship between η and R u and a significant cubic polynomial relationship ( p < 0.01) with cos θ , the following relationship can be used to describe how R u and cos θ affect sampling efficiency η : (27) η = a cos 3 θ + b R u cos 3 θ + c cos 2 θ + d R u c o s 2 θ + e c o s θ + f R u c o s θ + g R u + h where a–h are empirical coefficients.