The measurements here are similar to those in Example 12.31, except that here the students did the measuring at home, and the results suffered in accuracy.

a. Regress wingspan on the other two variables. Carry out the test of model utility and the tests for the two individual regression coefficients of the predictors.

b. Obtain the diagonal elements of the hat matrix (leverages). Identify the point with the highest leverage. What is unusual about the point? Given the instructor’s assertion that there were no students in the class less than five feet tall, would you say that there was an error? Give another reason that this student’s measurements seem wrong.
c. For the other points with high leverages, what distinguishes them from the points with ordinary leverage values?
d. Examining the residuals, find another student whose data might be wrong.
e. Discuss the elimination of questionable points in order to obtain valid regression results.

Example 12.31

Transcribed Image Text:

Wingspan 74 56 65 69 75 66 66 63 Foot 13.0 8.5 10.0 9.5 9.0 11.0 12.0 9.0 9.0 8.5 Height 75 66 69 66 54 72 75 63 66 63