An air-compressor manufacturer purchases mechanical components from two different suppliers (MechSup = 1 or 2) and electrical/motor components from three different suppliers (ElectSup = 1, 2, or 3), with final assembly being carried out by one of two technicians (Tech = 1 or 2). Following production, finished compressor units are tested to measure how much pressure they can exert (pounds per square inch, or psi). During the past few months, 100 compressors have been tested before shipment to customers, and the resulting data are listed in file XR02071.
a. Construct a simple tabulation in which the counts are according to which company supplied the mechanical components.
b. Construct a cross-tabulation describing the 100 compressors tested, using mechanical supplier and electrical/motor supplier as the categorization variables.
c. Construct a display showing the average pressure (psi) according to mechanical supplier and electrical/motor supplier. Which combination of mechanical and electrical/motor suppliers seems to result in the highest pressure exertion? The lowest pressure exertion?
d. Based on the crosstab and means in part (c), would it seem that any of the five suppliers should be examined further with regard to the effect their product might have on the final pressure capabilities of the finished product? Explain your answer.