tst ISO 7870-4

TSE ISO 7870-4 is the part of the control-chart family dedicated to cumulative sum (CUSUM) charts for process and quality control. In practical terms, it addresses the use of accumulated deviations to track whether a process is drifting away from its target, making it especially relevant when small but persistent shifts need to be detected rather than only large single-point changes.

How the cumulative sum approach works

The core idea behind CUSUM is to add successive departures from a target or reference value so that sustained process shifts become more visible over time. In general technical use, this makes the method valuable for monitoring and decision-making because it looks at direction and persistence of deviation, not just isolated observations. For attribute data, the same conceptual logic is applied through count-based results suited to discrete quality characteristics.

What this part covers

According to the scope, this part provides statistical procedures for setting up CUSUM schemes and general-purpose decision-making methods for monitoring, control, and retrospective analysis. In real-world quality practice, that means it supports the assessment of process performance, the investigation of quality shifts, and the review of historical data using cumulative-sum logic. It does not, from the supplied record alone, establish the detailed calculation rules, decision thresholds, or any specific software implementation; those details would come from the full text of the standard.

• It belongs to the control-chart family and treats process behaviour through time-based statistical monitoring.
• The cumulative-sum approach is well suited to detecting small but sustained shifts.
• It addresses both variable data and attribute data through general procedures.
• Retrospective analysis is part of its intended use alongside monitoring and control.
• This listing is the TSE edition of ISO 7870-4 and its status is withdrawn.