Chapter 2, Problem 2.171ACA

Steel rod quality. In his essay “Making Things Right,” W. Edwards Deming considered the role of statistics in the quality control of industrial products." In one example, Deming examined the quality-control process for a manufacturer of steel rods. Rods produced with diameters smaller than 1 centimeter fit too loosely in their bearings and ultimately must be rejected (thrown out). To determine whether the diameter setting of the machine that produces the rods is correct, 500 rods are selected from the day’s production and their diameters are recorded. The distribution of the 500 diameters for one day’s production is shown in the accompanying figure. Note that the symbol LSL in the figure represents the 1-centimeter lower specification limit of the steel rod diameters. There has been speculation that some of the inspectors are unaware of the trouble that an undersized rod diameter would cause later in the manufacturing process. Consequently, these inspectors may be passing rods with diameters that are barely below the lower specification limit and recording them in the interval centered at 1,000 centimeter. According to the figure, is there any evidence to support this claim? Explain.