Repeatability Sigma Chart Calculations: Combined Appraisers

Note: This chart is used when (Number of Trials > 10)

Plotted Statistic:

The sample standard deviation for each part for each Appraiser, calculated using the average from each Appraiser for the plotted part (x-baroper,pc)

Center Line:

The average of the plotted statistic

Control Limits:

where

S-bar is the Center Line (above)

c4 is based on a subgroup size equal to the number of trials

Note: Some authors, including AIAG, refer to the quantity (1+3(SQRT(1- c4^2))/c4)) as B4 , and (1-3(SQRT(1- c4^2))/c4)) as B3

See also:

Repeatability X-Bar Chart Calculations: Combined Appraisers

Repeatability Range Chart Calculations: Combined Appraisers (If (2 ≤ Number of Trials ≤ 10)

Repeatability X-Bar Chart Calculations: Per Appraiser

Repeatability Range Chart Calculations: Per Appraiser (If (2 ≤ Number of Trials ≤ 10)

Repeatability Sigma Chart Calculations: Per Appraiser (If (Number of Trials > 10)

Learn more about the Quality Improvement principles and tools for process excellence in Six Sigma Demystified (2011, McGraw-Hill) by Paul Keller, or his online Green Belt certification course ($499).