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Determination of Sample Size to Detect Quality Improvement in p-Charts

Summary: [This abstract is based on the authors' abstract.] Four methods of determining sample size for ρ-charts are examined to determine in each case whether the process in question has improved in quality. Two of the four methods compared are approximation methods previously discussed in the literature. The third is an exact method use both in this study and in an earlier research as a benchmark. The fourth method is a simple but accurate rule-of-thumb approach developed in this study.

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  • Topics: Sampling
  • Keywords: P chart (percent chart), Process improvement, Statistical process control (SPC), Sample size, Control limits
  • Author: Morris, R.L.; Riddle, E.J.
  • Journal: Quality Engineering