Aircraft primer paints are applied to aluminium surfaces by two methods: dipping and spraying. The purpose of the primer is to improve paint adhesion; some parts can be primed using either application method. An engineer interested in learning whether three different primers differ in their adhesion properties performed a factorial experiment to investigate the effect of paint primer type & application method on paint adhesion. Three specimens were painted with each primer using each application method, a finish paint was applied, and the adhesion force was measured. The 18 runs from this experiment were run in random order. The resulting data are shown in Table 12-1. The circled numbers in the cells are the cell totals. The objective of the experiment was to determine which combination of primer paint and application method produced the highest adhesion force. It would be desirable if at least one of the primers produced high adhesion force regardless of application method, as this method add some flexibility to the manufacturing process.