Question: Runners are concerned about their form when racing. One measure of form is the stride rate, the number of steps taken per second. As running speed increases, the stride rate should also increase. In a study of 21 of the best American female runners, researchers measured the stride rate for different speeds. The following table gives the speeds (in feet per second) and the mean stride rates for these runners:

Speed 15.86 16.88 1730 18.62 19.97 21.06 22.11

Stride rate 3.05 3.12 3.17 3.25 336 3.46 3.55

(a) Plot the data with speed on the .s axis and stride rate on they axis. Does a straight line adequately describe these data?

(b) Find the email ion of the regression line of stride rate on speed. Draw is line on your plot.

(c) For each of the speeds given, obtain the predicted value of the snide rate and the residual. Verify that the residuals add to zero.

(d) Plot the residuals against speed. Describe the pattern. What does the plot indicate about the adequacy of the linear fit? Are there any potentially influential observation?