The Red Beads Experiment What was wrong with management’s decision to keep the place open with the best workers? What is the meaning of the best workers? Best when? Over what time period? What rational basis was there for the prediction that the best workers in the past would be best in the future? How might the willing workers have improved their output of white beads had they been allowed to try out suggestions for improving procedures? What did the control charts tell us? Can the control chart provide prediction of variation in the number of red beads?

The Funnel Experiment What does Deming mean by tampering? Provide examples of Rules 2, 3, and 4 of the Funnel Experiment.

Taguchi’s view of quality “ Quality is the loss imparted to the customer in using the product as a result of functional variation and harmful effects.” Functional Variation: Deviation of performance from that intended by engineering design Harmful Effects: Negative effects encountered during use that are unrelated to function

Our View of Quality Should: Move the quality issue upstream to engineering design Move the quality issue downstream to customers Promote prevention rather than detection Promote continual pursuit of never ending improvements

The Conformance to Specifications Model vs. The Loss Function Model Traditional Western Views Alternative (Taguchi) Model:

The Loss Function Y = k(x - nominal) 2 Where, Y = loss incurred k = a constant to be determined for each application x = the actual measurement of the part nominal = the optimal measurement of the part Example: The specifications for the diameter of an axle are25mm ±.25 mm. If the diameter is out of spec the axle must be scrapped at a cost of $4.00. What is the loss function for this application?

Consider two methods (A and B) that are proposed to produce the axles. The distribution of axle diameters under the two methods is shown below. Suppose that one million of these axles are produced per year. Which method would you prefer ?

Taguchi’s Quality of Design Quality is defined as loss due to functional variation Loss due to functional variation is caused by: Outer Noise: Inner Noise: Variational Noise