AAOM Handbook

MP.13 Determine the required measurement precision/accuracy

Context

The measurement precision/accuracy will determine the minimum level of variation that can be identified (referred to as the quantisation level). Any variation that is less than this will not be seen. Selecting the quantisation level for measuring performance is a trade-off between the detail needed to determine that performance is within specifications and the effort/cost of achieving that accuracy. In most instances today we have inexpensive and highly accurate technology that can provide a much higher level of resolution than is necessary to help us understand the capability of a process.

Purpose

To identify the minimum level of accuracy required to expose significant variation

Quantity One statement of the level of accuracy required for each measure.

Quality

In practice, a Capability Histogram that is based on 15 to 20 quantisation steps of the full range of variation typically provides enough detail. The quantisation level can generally therefore be set to the minimum level of variation that you wish to observe.

Resources

This task is completed by the manager responsible for the process.

Time The task should be completed prior to measures being developed