Using the data for Case Study 7.1, (a) Plot Y = WATER versus X = STIME to show that the relationship is not linear. (b) Transform both Y and X by taking the logarithms, and plot the data again. Is the...

Using the data for Case Study 7.1,

(a) Plot Y = WATER versus X = STIME to show that the relationship is not linear.

(b) Transform both Y and X by taking the logarithms, and plot the data again. Is the relationship more nearly linear? What difficulties remain?

(c) Calculate the parameter estimates, the predicted values, and the residuals for the transformed data. Then plot the residuals against the predicted value.

Does this plot alert you to any problems with the model?