Shewhart control chart in which the ranges of measured quantity values are plotted against time.
Notes: - The range is the greatest measured quantity value minus the least measured quantity value.
- Warning and action limits are given in tables (for example) as a function of the number of measured quantity values (\(n\)) taken to obtain the range and of the expected average range.
- Nordtest advises that for Shewhart range charts, the best samples to be used are test samples selected from among the samples to be analysed in that analytical run.
Source:
PAC, 2021, 93, 997. 'Metrological and quality concepts in analytical chemistry (IUPAC Recommendations 2021)' on page 1041 (https://doi.org/10.1515/pac-2019-0819)