The repair manager for a manufacturer of desktop computers noticed that a large number of units were being returned for repairs. The manager selected a sample of seven returned units and noticed that these units were distinguished by the following characteristics. Units 1 and 3 had type X circuitry and were shipped to coastal regions. Units 2 and 7 were sold to business customers, were manufactured in the Kansas City plant, and were shipped to coastal regions. Units 4 and 5 were used to play computer games and were manufactured in the Kansas City plant. Units 6 and 7 were shipped to large cities and had type X circuitry. Unit 4 was shipped to a large coastal city. Units 2 and 3 were shipped to large cities. Unit 5 was shipped to a coastal region and had type X circuitry. Unit 3 was sold to a business customer who used it to play computer games. Unit 1 was used to play computer games and was manufactured in the Kansas City plant. Finally, Unit 6 was sold to a business customer in a coastal region. Among these six distinguishing characteristics the manager concluded that salty air caused the computers to break down. Construct a table that supports this conclusion. Which one of Mill's methods did the manufacturer use? What sense of causality is involved in the conclusion?