ISO/TC 69/SC 4/WG 12 - Implementation of statistical Process Control

This document describes examples for software validation for SPC software implementing the standards of the ISO 7870 series on control charts and the ISO 22514 series on capability and performance. In detail ISO 7870‑2, ISO 22514‑2 and ISO 22514‑8 are covered. It provides data sets and test results for testing the implementation of the evaluation methods described in these standards. This includes the detection of out of control situations as well as the calculation of sample statistics and process capability indices. The test examples cover the following situations: a) General: — different sample and subgroup sizes, accuracy of calculation for large/small numbers; b) ISO 22514 series: — calculation of sample statistics for location and dispersion; — different distribution models; c) ISO 7870‑2: — calculation of control limits; — visualization of data (histogram, control charts); — detection of out of control situations.

ISO 11462-2:2010 provides a catalogue of tools and techniques to help an organization in planning, implementation and evaluation of an effective statistical process control (SPC) system. This catalogue gives tools and techniques that are essential for the successful realization of the SPC elements.

Statistical process control (SPC) concerns the use of statistical techniques and/or statistical or stochastic control algorithms to achieve one or more of the following objectives: a) to increase knowledge about a process; b) to steer a process to behave in the desired way; c) to reduce variation of final-product parameters, or in other ways improve performance of a process. These guidelines give the elements for implementing an SPC system to achieve these objectives. The common economic objective of statistical process control is to increase good process outputs produced for a given amount of resource inputs. NOTE 1 SPC operates most efficiently by controlling variation of a process parameter or an in-process product parameter that is correlated with a final-product parameter; and/or by increasing the process's robustness against this variation. A supplier's final-product parameter may be a process parameter to the next downstream supplier's process. NOTE 2 Although SPC is concerned with manufactured goods, it is also applicable to processes producing services or transactions (for example, those involving data, communications, software, or movement of materials). This part of ISO 11462 specifies SPC system guidelines for use _ when a supplier's capability to reduce variation in processes associated with design or production needs to be proven or improved; or _ when a supplier is beginning SPC implementation to achieve such capability. These guidelines are not intended for contractual, regulatory or certification use.