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5. Process Improvement
5.6. Case Studies
5.6.2. Sonoluminescent Light Intensity Case Study

Important Factors: Half-Normal Probability Plot

Purpose The half-normal probability plot is used to distinguish between important and unimportant effects.
Sample Half-Normal Probability Plot the half-normal probability plot identifies the important factors
Conclusions from the Half-Normal Probability Plot We can make the following conclusions from the half-normal probability plot.
  1. The points in the plot divide into two clear clusters:

    • An upper cluster (|effect| > 60).
    • A lower cluster (|effect| < 20).

  2. The upper cluster contains the effects:

      X2, X7, X1*X3 (and confounding), X1, X3, X2*X3 (and confounding), X1*X2 (and confounding)

    These effects should definitely be considered important.

  3. The remaining effects lie on a line and form a lower cluster. These effects are declared relatively unimportant.

  4. The effect id's and the confounding structure are given on the far right (e.g., 13:13+27+46).
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