Consider the modeling of aerobic fitness described in Problem 13.2.4 and the data set in DS 13.2.4. Suppose that a model is used with V02-max as the dependent variable and with heart rate at rest and percentage body fat as input variables.
(a) Make plots of the residuals against the lilted values and against each of the two input variables. Are vi alerted to any problems with the regression model
(b) Make a plot of the i CM dual-, against the variable weight. Why does this plot confirm that the variable weight is not needed in the regression model?
(c) Verify that there are no points with an unusually I art influence on the regression model.
(d) Verify that there is one point with a standardized residual of -2.15.