A paint manufacturer is attempting to improve the process that fills the 1-gallon containers. The foreperson has suggested that the nozzle can be made from several different alloys. Furthermore, the way that the process “knows” when to stop the flow of paint can be accomplished in two ways: by setting a predetermined amount or by measuring the amount of paint already in the can. To determine what factors lead to variation, an experiment is conducted. For each of the four alloys that could be used to make the nozzles and the two measuring devices, five cans are filled. The amount of paint in each container is precisely measured. The data in liters were recorded in the following way:
Column 1: Device 1, rows 1 to 5 alloy A, rows 6 to 10 alloy B, etc.
Column 2: Device 2, rows 1 to 5 alloy A, rows 6 to 10 alloy B, etc.
Can we infer that the alloys, the measuring devices, or both are sources of variation?