Data transformation, particularly the Box-Cox power transformation, is a remedial action that may help to make data normal. By understanding transformation and the Box-Cox method, practitioners will be better prepared to work with non-normal data.
Some people believe that it is not necessary to transform non-normal data before creating an individuals control chart. The chart, however, is not robust to non-normally distributed data. Therefore, it is important to use an alternate approach.
Practitioners can benefit from an overview of normal and non-normal distributions, as well as familiarizing themselves with some simple tools to detect non-normality and techniques to accurately determine whether a process is in control and capable.