The Red Beads Experiment

1
The Red Beads Experiment

• What was wrong with managements 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?

2
The Funnel Experiment

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

3
Taguchis 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

4
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

5
The Conformance to Specifications Model vs. The
Loss Function Model

• Traditional Western Views
• Alternative (Taguchi) Model

6
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?

7
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
?
8
Taguchis 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