Distribution of the residuals. Some statistical methods require that the residuals from a regression line have a Normal distribution. The residuals for the nonexercise activity example are given in Exercise 4.75 (page 192). Is their distribution close to Normal? Make a Normal quantile plot to find out.
Exercise 4.75
Find the sum of the residuals. Here are the 16 residuals for the NEA data rounded to two decimal places:
Find the sum of these residuals. Note that the sum is not exactly zero because of roundoff error.