Explanation: There are two ways invented for the representation of the Cusums on the Cusum charts; namely Tabular Cusum, and V-mask form of the Cusum.

Explanation: There are two ways of representing the Cusums. The first one is the tabular (or Algorithmic) Cusum, and the second one is the V mask form of Cusum.

Explanation: The tabular Cusum is generally made to monitor the changes occurring in the mean of the process with respect to the time. This is preferred over the V-mask type.

Explanation: For the construction of the tabular cusum charts, it is assumed that the variable for which the Cusum charts are to be plotted, varies on a normal distribution.

Explanation: Tabular Cusum charts are made with the assumptions that, the selected variable varies on normal distribution with a known mean and standard deviation. The standard deviation estimate may also be used.

Explanation: If the process standard deviation increases, Si+ value will be increased consequently. It will eventually exceed the decision interval h and we will get an out-of-control signal.

Explanation: If the process becomes out-of-control with low value of the process standard deviation, the value of Si– will increase and eventually exceed the decision interval, h.

Explanation: Although it is customary to plot the cusum charts for mean and cusum charts for standard deviation on different graphs, Hawkins (1993a) was the first person who recommended to plot them on same graph.

Explanation: When the rational subgrouping procedure is adopted with sample size n>1, the cusum charts are built by simply replacing xi by xi and σ by σ/√n.

Also the cusum values, whether it is the upper cusum, or lower cusum, are either zero or positive. So even if the value of C–i-1+S2+k is lesser than (-1), the value of Ci– will be zero.

Explanation: There are two procedures to plot the cusum charts. One is called the tabular cusum, and the other is called the V-mask procedure. The V-mask procedure was first introduced by Barnard (1959).