平均极差分布及控制图常数表

子组内

观察次数A2D3D4

2 1.8800 3.267

3 1.0230 2.575

40.7290 2.282

50.5770 2.115

60.4830 2.004

70.4190.076 1.934

80.3730.136 1.864

90.3370.184 1.816

100.3080.223 1.777 110.2850.256 1.744 120.2660.284 1.716 130.2490.308 1.692 140.2350.329 1.671 150.2230.348 1.652