The specifications are taken from the grid of the project. The selector at the top of the page allows you to choose which ones to examine.
Two concepts underpin reading and are worth understanding above all else:
- The sample consists of a set of measurements taken together or a rational subset. It forms the basis for control charts.
- The Rehearsal distinguishes between multiple measurements within the same sample.
This breakdown determines how the variance is calculated short term, which refers to the variation within a sample, as opposed to overall dispersion, which includes variations from one sample to another. This is the key difference between Cp and Pp (see the appendix).
⚠️ An arbitrary division into samples distorts this separation. Grouping measurements that were not taken together increases short-term variability and masks trends.