(This is on pg. 64-65 of our textbook.)
(We will likely not work through this entire example that is in the book. I recommend reading through this on your own.)
Blakely Tires is a U.S. producer of automobile tires. In an attempt to learn about the conditions of its tires on automobiles in Texas, the company has obtained information for each of the four tires from 116 automobiles with Blakely brand tires that have been collected through recent state automobile inspection facilities in Texas. The data obtained by Blakely includes the position of the tire on the automobile (left front, left rear, right front, right rear), age of the tire, mileage on the tire, and depth of the remaining tread on the tire. Before Blakely management attempts to learn more about its tires on automobiles in Texas, it wants to assess the quality of these data.
The tread depth of a tire is a vertical measurement between the top of the tread rubber to the bottom of the tire’s deepest grooves, and is measured in 32nds of an inch in the United States. New Blakely brand tires have a tread depth of 10/32nds of an inch, and a tire’s tread depth is considered insufficient if it is 2/32nds of an inch or less. Shallow tread depth is dangerous as it results in poor traction and so makes steering the automobile more difficult. Blakely’s tires generally last for four to five years or 40,000 to 60,000 miles.
Let’s assess the quality of these data by determining which (if any) observations have missing values for any of the variables in the data.
