An Adaptation of Quality Control Chart Methods to Bacterial Vaccine Potency Testing

Abstract

The determination of values, even repeated measurements of a certain dimension of a single inanimate article, is subject to errors or lack of precision. Likewise, in the mass production of articles designed to be alike, determination of a certain dimension or attribute of each article produced yields a series of values differing from unit to unit. If these values are plotted as a frequency distribution, they describe a pattern characteristic of the process under consideration. Every process, no matter now rigorous the attempt to control it, is subject to inherent variability, and the pattern of variability for each process is unique unto itself. When any change from the basic pattern occurs, some new source of variability must have entered the process. The methods of quality control are based on this principle. Prior to World War II, Shewhart (1931, 1939) and Pearson (1935) studied the application of statistical methods to problems pertaining to the control of variability of manufactured articles and introduced' the basic techniques of modern quality control. The urgent demand for testing procedures combining accuracy and economy, occasioned by the accelerated production schedules of

Applications and Experiences of Quality Control

“…In the nineteen-twenties, Walter A. Shewart, with a group of experts, established the scientific ground for quality control at Bell Telephone Laboratories Shewhart (1931). It is only in the nineteen fifties that quality control procedures were employed to ensure the precision of hospital laboratory machines used in biology, nuclear medicine, drug industry and other medical domains Anderson (1982); Batson et al (1951); Brookeman (1978); Hollinger & Lansing (1956); Loynd (1962); Pribr & Shuster (1967); Waid & Hoffmann (1955). Later, in the nineteen seventies, the use of these methods shifted to the monitoring of the effect of treatments on patients Kinsey et al (1989); Morgan et al (1987); Robinson & Williamson (1974); Walters & Griffin (1986); Wohl (1977), and then to other more complex levels such as the performance of departements Chamberlin et al (1993); The Inquiry into the management of care of children receiving complex heart surgery at the Bristol Royal Infirmary (2001), hospitals Sellick (1993), regions Tillett & Spencer (1982) or nation-wide processes Hand et al (1994).…”