BS ISO 7870-3:2020 pdf free.Control charts Acceptance control charts.
BS ISO 7870-3 This document gives guidance on the uses of acceptance control charts and establishes general procedures for determining sample sizes, action limits and decision criteria. An acceptance control chart should be used only when: a) the within subgroup variation is in-control and the variation is estimated efficiently;b) a high level of process capability has been achieved.
An acceptance control chart is typically used when the process variable under study is normally distributed; however, it can be applied to a non-normal distribution. The examples provided in this document ilustrate a variety of circumstances in which this technique has advantages; these examples provide details of the determination of the sample size, the action limits and the decision criteria.The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.Is0 3534-1, Statistics 一Vocabulary and symbols一Part 1: General statistical terms and terms used in probability ISO 3534-2, Statistics一Vocabulary and symbols一Part 2: Applied statistics In the pursuit of an acceptable product or service, there often is room for some latitude in the ability to centre a process around its target level. The contribution to overall variation of such location factors is additional to the inherent random variability of individual elements around a given process
level. In most cases, some shifts in process level must be expected and can be tolerated. These shifts usually result from an assignable cause that cannot be eliminated because of engineering or economic considerations. They often enter the system at infrequent or irregular intervals, but can rarely be treated as random components of variance.There are several seemingly different approaches to treating these location factors contributing variation beyond that of inherent variability. At one extreme is the approach in which all variability that results in deviations from the target value must be minimized. Supporters of such an approach seek to improve the capability to maintain a process within tighter tolerance limits so that there is greater potential for process or product quality improvement.BS ISO 7870-3 pdf download.