Discussion: integrating SPC and APC

We would like to thank Box and Kramer for a thought-provoking commentary on a very timely topic. We found their tone much more open-minded than the typical “Shewhart bashing” currently in vogue. We believe that the authors have accomplished their objective of removing misunderstanding in this area, particularly for explaining that the fundamental issue is not choosing statistical process control (SPC) or automatic process control (APC), but how to integrate them effectively. We would like to note that in 1944, Deming suggested that “good engineering control of the process” must be part of any qualitycontrol program (Deming 1944, p. 177). Our interest in this topic is primarily from an applications point of view; hence we will focus on the practical issues versus the theoretical.