Statistical process monitoring in the twenty-first century

The term ‘Statistical Process Control’ (SPC) refers to a loosely defined collection of techniques for monitoring a process so as to prevent deterioration and facilitate improvement. These techniques are used for monitoring a process (Box and Kramer, 1992), so the phrase ‘process monitoring’ seems more appropriate than ‘process control’ and I have used the former in the title. However, this is just a matter of terminology: SPC techniques always were about monitoring rather than control, and as the use of the word control causes problems – as we will see below – it is sensible to replace it with a more accurate term. I will use the term SPC/M in this chapter.