Selecting a Control Chart:

Data Type	Measurement Type	Subgroup Size	Control Chart
Variable	Individual	1	Individual & MR (Moving Range)
Variable	Continuous	2-9 (small)	X-bar & R
Variable	Continuous	10+ (large)	X-bar & S
Attribute	Defective	Constant	p Chart
Attribute	Defective	Variable	np Chart
Attribute	Defect	Constant	c Chart
Attribute	Defect	Variable	u Chart

Control Chart Limits (UCL, LCL and Mean)

Control Chart	Center Line	Upper Control Limit (UCL)	Lower Control Limit (LCL)
X-bar Chart	$$\bar{X}$$	$$\bar{X} + A_2 \bar{R}$$	$$\bar{X} - A_2 \bar{R}$$
R Chart	$$\bar{R}$$	$$D_4 \bar{R}$$	$$D_3 \bar{R}$$
S Chart	$$\bar{S}$$	$$B_4 \bar{S}$$	$$B_3 \bar{S}$$
p Chart	$$\bar{p}$$	$$\bar{p} + 3\sqrt{\frac{\bar{p}(1-\bar{p})}{n}}$$	$$\bar{p} - 3\sqrt{\frac{\bar{p}(1-\bar{p})}{n}}$$
np Chart	$$n\bar{p}$$	$$n\bar{p} + 3\sqrt{n\bar{p}(1-\bar{p})}$$	$$n\bar{p} - 3\sqrt{n\bar{p}(1-\bar{p})}$$
c Chart	$$\bar{c}$$	$$\bar{c} + 3\sqrt{\bar{c}}$$	$$\bar{c} - 3\sqrt{\bar{c}}$$
u Chart	$$\bar{u}$$	$$\bar{u} + 3\sqrt{\frac{\bar{u}}{n}}$$	$$\bar{u} - 3\sqrt{\frac{\bar{u}}{n}}$$

Sample Size (n)	D3	D4	B3	B4	d2	A2
2	0	3.267	0	2.606	1.128	1.880
3	0	2.574	0	1.880	1.693	1.023
4	0	2.282	0.030	1.604	2.059	0.729
5	0	2.114	0.118	1.427	2.326	0.577
6	0.030	2.004	0.185	1.287	2.534	0.483
7	0.118	1.924	0.235	1.182	2.704	0.419
8	0.185	1.864	0.270	1.099	2.847	0.373
9	0.235	1.816	0.296	1.032	2.970	0.337
10	0.270	1.777	0.315	0.975	3.078	0.308
11	0.296	1.744	0.330	0.927	3.173	0.285
12	0.315	1.717	0.342	0.886	3.258	0.266
13	0.330	1.693	0.352	0.850	3.336	0.249
14	0.342	1.672	0.361	0.817	3.407	0.235
15	0.352	1.653	0.369	0.789	3.472	0.223
25	0.435	1.541	0.447	0.668	4.459	0.153
50	0.576	1.427	0.550	0.560	6.864	0.114
100	0.704	1.341	0.620	0.481	10.577	0.080