A Robust Control Chart for Monitoring Dispersion

Table 3

ARL₁(𝛿) for dispersion shifts in the heavy tailed distribution 𝑡(3), for several values of the change time 𝜏.

𝜏	𝛿	𝑡(3)/√3×𝛿
		MWCPM	ROBUSTD	NLREWMA
50	2.0	278	50.7	80.2
	3.0	179	12.5	25.0
	0.5	707	79.8	386.8
	0.33	769	22.6	312.8
300	2.0	104	18.6	25.3
	3.0	52.3	8.4	10.5
	0.5	1144	32.1	307.9
	0.33	728	19.0	72.7