Table 1.

ARL₀ values for the T² and MEWMA control charts (t-distribution with different degrees of freedom).

	ν
ARL0 T2	5	8	10	15	20	30	40	50	100	1000
$\varphi$ = 0
$T_{total}^2$	40.57	63.34	78.61	104.34	119.92	141.59	157.11	162.77	178.58	198.37
$T_{\text{stage2}}^{\text{2}}$	79.59	126.70	155.50	206.17	240.81	285.63	305.92	325.68	358.68	389.368
$T_{\text{stage1}}^{\text{2}}$	81.55	126.60	154.54	208.82	238.72	283.11	308.74	329.11	357.77	389.18
$\varphi$ = 0.1
$T_{\text{total}}^{\text{2}}$	40.71	64.13	79.07	104.96	120.96	142.16	154.78	163.02	178.90	198.94
$T_{\text{stage2}}^{\text{2}}$	81.43	126.31	155.81	208.57	242.53	287.05	312.87	335.89	361.68	394.95
$T_{\text{stage1}}^{\text{2}}$	81.55	126.60	154.54	209.82	240.72	285.11	310.74	332.11	359.77	395.18
$\varphi$ = 0.5
$T_{\text{total}}^{\text{2}}$	40.61	64.02	76.79	104.30	120.41	144.69	151.69	164.59	180.89	196.54
$T_{\text{stage2}}^{\text{2}}$	80.12	130.19	154.39	204.63	242.15	283.31	303.11	330.70	351.18	391.36
$T_{\text{stage1}}^{\text{2}}$	79.68	128.82	153.30	208.46	242.45	284.01	306.85	332.89	355.11	393.93
$\varphi$ = 0.9
$T_{\text{total}}^{\text{2}}$	27.34	40.22	64.33	76.30	102.75	121.43	143.74	157.29	162.79	179.59
$T_{\text{stage2}}^{\text{2}}$	54.22	80.04	125.83	155.69	204.39	239.42	284.57	311.89	332.92	371.61
$T_{\text{stage1}}^{\text{2}}$	54.75	79.94	127.54	154.73	204.97	239.86	284.35	310.56	330.89	368.56
	ν
ARL0 MEWMA	5	8	10	15	20	30	40	50	100	1000
$\varphi$ = 0
$\text{MEWM}{\text{A}}_{\text{total}}$	107.01	144.84	161.17	175.98	179.35	189.61	190.94	195.99	199.22	202.87
$\text{MEWM}{\text{A}}_{\text{stage2}}$	213.71	290.70	314.42	345.08	360.99	380.71	381.98	381.12	389.28	397.89
$\text{MEWM}{\text{A}}_{\text{stage1}}$	213.71	290.70	314.41	345.08	360.99	380.71	381.97	381.12	389.27	397.89
$\varphi$ = 0.1
$\text{MEWM}{\text{A}}_{\text{total}}$	107.01	144.84	161.17	175.98	179.35	189.61	191.93	195.993	199.22	204.87
$\text{MEWM}{\text{A}}_{\text{stage2}}$	214.17	287.50	315.59	344.63	363.02	378.29	382.79	378.68	392.49	400.05
$\text{MEWM}{\text{A}}_{\text{stage1}}$	213.71	290.70	314.41	345.08	360.99	380.71	381.97	381.12	389.27	397.89
$\varphi$ = 0.5
$\text{MEWM}{\text{A}}_{\text{total}}$	108.49	145.85	157.54	174.88	181.29	192.16	192.63	197.13	198.86	201.48
$\text{MEWM}{\text{A}}_{\text{stage2}}$	216.33	288.82	312.00	342.65	357.86	380.20	381.85	385.88	392.52	396.11
$\text{MEWM}{\text{A}}_{\text{stage1}}$	217.44	285.84	314.92	340.87	355.97	378.40	383.69	386.72	398.99	399.98
$\varphi$ = 0.9
$\text{MEWM}{\text{A}}_{\text{total}}$	108.43	144.43	157.47	173.54	179.31	188.33	193.94	194.59	198.09	201.59
$\text{MEWM}{\text{A}}_{\text{stage2}}$	215.53	285.84	316.11	346.10	363.97	372.64	384.71	390.23	393.07	401.82
$\text{MEWM}{\text{A}}_{\text{stage1}}$	214.17	281.50	315.58	344.62	363.02	373.29	382.79	388.67	392.48	398.82