Morais, M. C. ; Knoth, S.
Wiley StatsRef: Statistics Reference Online, (2020),
Each specification that is not satisfied by a unit of a product is considered a defect, a demerit or, more generally, a nonconformity. c-chart is the term used in quality control for a chart in which the count of nonconformities in each of a sequence of samples of constant size is plotted against the serial number of the sample. We describe the c-chart with 3-sigma control limits, provide examples using R (programming language), and discuss a technique to mitigate its poor performance.