Chapter 12, Problem 112SE

a.

To determine

Obtain a quadratic regression model $y={\beta }_0+{\beta }_{1}x+{\beta }_{11}{x}^2+\epsilon$.

b.

To determine

Test for the statistical significance of the regression at level of significance $\alpha =0.05$ and draw necessary conclusions.

c.

To determine

Test the contribution of the quadratic term to the model at level of significance $\alpha =0.05$.

d.

To determine

Plot the residuals versus $\widehat{y}$ and versus each of the regressors and provide a discussion

e.

To determine

Draw a normal probability plot of the residuals for the model.

Comment regarding the normality assumption.