The data shown in Appendix D, Table 18 give the sediment yield, 3. runoff, z, and precipitation, for 19 streams in New Zealand.

a. Fit the linear regression of y on 2, and 2. h. Compute the residuals and plot them against the predicted values. Comment on the need for a transformation.

e. Use the Box-Cox and/or the Atkinson method to suggest transformations on the response and the predictors.

d. Fit a linear model for the transformed data in which logarithms of each variable are used.

e. Determine the prediction interval for the response at the mean value of xy and xy for the transformed model and compare with the prediction computed for the model in part a

f. Plot the residuals against the predicted values for this model and comment on any unusual features