Note: This chart is used when Number of Appraisers > 10
The sample standard deviation of Appraiser averages for each part, calculated using the average for the plotted part (x-barpc)
The average of the plotted statistic
where S-bar is the Center Line (above) and c4 is based on a subgroup size m = the number of Appraisers.
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