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Distribution-free Phase I Control Charts for Subgroup Location
Journal of Quality Technology
  • Allison L. Jones-Farmer, Auburn University
  • Victoria Jordan, Anderson Cancer Center
  • Charles W. Champ, Georgia Southern University
Document Type
Publication Date
Statistical quality control often relies on the completion of a Phase I study. Many Phase I control charts, however, rely on an assumption of normally distributed process observations that may not be reasonable in the early stages of process control. A literature review shows no purely distribution-free Phase I control chart methods currently exist. This study introduces a distribution-free method for defining the in-control state of a process and identifying an in-control reference sample that can be used to estimate the process parameters for a Phase II procedure. The proposed procedure compares favorably with the traditional X-bar chart when the process is normally distributed and better than the X-bar chart when the process distribution is skewed or heavily tailed.
Citation Information
Allison L. Jones-Farmer, Victoria Jordan and Charles W. Champ. "Distribution-free Phase I Control Charts for Subgroup Location" Journal of Quality Technology Vol. 41 Iss. 3 (2009) p. 304 - 316
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