# Question

Refer to the data of Exercise 13.34.

a. Fit a cubic model y = β0 + β1x + β2x2 + β3x3 + ɛ.

b. Test for lack of fit of the model at the α = .05 level.

c. Evaluate the normality and constant variance assumptions.

In exercise

a. Fit a cubic model y = β0 + β1x + β2x2 + β3x3 + ɛ.

b. Test for lack of fit of the model at the α = .05 level.

c. Evaluate the normality and constant variance assumptions.

In exercise

## Answer to relevant Questions

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