A bioengineer wants to model the amount (y) of carbohydrate solubilized during steam processing of peat as a function of temperature (x_{1}), exposure time (x_{2}), and pH value (x_{3}). Data collected for each of 15 peat samples were used to fit the model

E(y) =β_{o} + β_{1}x_{1} + β_{2}x_{2} + β_{3}x_{3}

A summary of the regression results follows:

Based on these results, the bioengineer concludes that none of the three independent variables, x_{1}, x_{2}, and x_{3}, is a useful predictor of carbohydrate amount, y. Do you agree with this statement? Explain.