Consider the model y e x = + 1 2 3 This is called the Mitcherlich equation, and it is often

Consider the model y e x =− + − θθ ε θ 1 2 3 This is called the Mitcherlich equation, and it is often used in chemical engineering. For example, y may be yield and x may be reaction time.

a. Is this a nonlinear regression model?

b. Discuss how you would obtain reasonable starting values of the parameters θ1 , θ2 , and θ3 .

c. Graph the expectation function for the parameter values θ1 = 0.5,

θ2 = − 0.10, and θ3 = 0.10. Discuss the shape of the function.

d. Graph the expectation function for the parameter values θ1 = 0.5, θ2 = 0.10, and θ3 = 0.10. Compare the shape with the one obtained in part c.