1. Calculate the residuals from the least-squares fitted model for the pH mea surement data set phmeas .txt and plot them against the fitted values. What does this indicate about the fitted model?
2. For the LW and SW data set lwsw .txt plot the residuals from the least squares model against the fitted values and comment on the plot.
3. For the adhesion data set adhesion2 .txt plot the residuals for the least squares model against the fitted values and comment on the plot.
4. In Example 3.5.5 (p. 73), compute all the residuals for the model Y = j30 + /32X2 + E.