Parameter,Description
μᵢₙ,"The mean of the performance metric when the process is in-control, i.e., when there is no performance drift"
ARL₀,Expected number of days before the control chart signals a false detection
σᵢₙ,The in-control standard deviation of the metric
ARL₁,Expected number of days before the control chart signals a true detection
k,"The normalized reference value, which is related to the magnitude of change that one is interested in detecting. k = 0.5 is the default choice for detecting a unit standard deviation change"
Sₕᵢ,Cumulative sum of positive changes in the metric
h,The normalized threshold or control limit (default = 4). This threshold determines when the control chart signals a detection
Sₗₒ,Cumulative sum of negative changes in the metric