=+a. Here is output from fitting the model with the three xi

’s as predictors:

Predictor Coef SE Coef T p Constant -0.002997 0.007639 -0.39 0.697 fib cont -0.012125 0.007454 -1.63 0.111 fib lngth -0.0003020 0.0001676 -1.80 0.078 hyd grad 0.102489 0.004711 21.76 0.000 s = 0.0162355 R-sq = 91.6% R-sq(adj) = 91.1%

Source DF SS MS F p Regression 3 0.129898 0.043299 164.27 0.000 Residual Error 45 0.011862 0.000264 Total 48 0.141760