highly significantp <0.01
Change extremely significant to highly significant ( p <0.01).
Change extremely significant to highly significant ( p <0.01).
As shown in Table 2, the coefficient of determination R 2 was extremely significant, and the model with simple ratio index (y = 2.517x + 0.381, R 2 = 0.787, RMSE = 0.187) has the best goodness of fit.