Control Chart Coefficients Table

The captioned X bar and S Charts table which specify the c4, B3, B4, B5, B6 and A3 coefficients for sample size n. This control table is extensively used to determine the stability of processes in many industries when the sample size is more than 8. You can use X bar and R Charts when your sample size is less than 8.

X bar and S Charts

X bar and S Charts
Charts for Standard Deviation (S)Charts for Averages
Divisor to Estimate
σx
Factors for
Control Limits
Control Limit
Factor
Subgroup
Size n
c4B3B4B5B6A3
20.797903.26702.6062.659
30.886202.56802.2761.954
40.921302.26602.0881.628
50.940002.08901.9641.427
60.95150.0301.9700.0291.8741.287
70.95940.1181.8820.1131.8061.182
80.96500.1851.8150.1791.7511.099
90.96930.2391.7610.2321.7071.032
100.97270.2841.7160.2761.6690.975
110.97540.3211.6790.3131.6370.927
120.97760.3541.6460.3461.6100.886
130.97940.3821.6180.3741.5850.850
140.98100.4061.5940.3991.5630.817
150.98230.4281.5720.4211.5440.789
200.98690.5101.4900.5041.4700.680
250.98960.5651.4350.5591.4200.606

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