Managing Quality

Chapter 19. Statistical Process Control

B. G. Dale and P. Shaw

Introduction

In recent years statistical process control (SPC) has become a fashionable buzzword in 'industry', but the concept is not new; its roots can be traced back to the work of Shewhart (1931) at Bell Laboratories in 1923. The control charts in use today for monitoring processes are little different from those developed by Shewhart for distinguishing between controlled and uncontrolled variation, albeit statisticians continue to argue their theoretical foundations. Also in the late 1920s Dudding, a British statistician, was carrying out work along similar lines to those of Shewhart. The British Standards Institution published two early standards on SPC – BS 600 (1935), which was their first standard on quality control, and BS 600R (1942). Statistical process control was used by American industry during the Second World War to assist with the quality control of war materials, and the now defunct British Productivity Council produced, over 30 years ago, a film entitled Right First Time, which provides a vivid illustration of the use of SPC by a UK automotive manufacturer.

The 1980s witnessed a resurgence in statistical quality control in general, and SPC in particular. Many words have been written about it and a considerable number of training courses have been offered on the technique by a wide variety of organizations. The trend is such that it might appear to a casual observer that an entire industry has emerged ...