The cars were driven 5000 miles, and tire wear, as measured by a standard procedure, turned out to be: (a) What car had the hot-rod driver? Does the presence of the hot-rod driver invalidate the...

The cars were driven 5000 miles, and tire wear, as measured by a standard procedure, turned out to be:

(a) What car had the hot-rod driver? Does the presence of the hot-rod driver invalidate the experiment?

(b) Test for the equality of tire effects, the equality of position effects, and the equality of car effects.