Process Capability: Is it Just a Quality Metric?
*Helen Strickland, GSK 


In the first half of the 20th century, W.A. Shewhart and W.E. Deming promoted the view that the long-range contribution of Statistics depends not so much upon getting a lot of highly trained statisticians into industry as it does in creating a statistically minded generation of physicists, chemist, engineers and others who will in some way have a hand in developing and directing the production processes of tomorrow. Well into the second decade of the 21st century, the contribution of Statistics in the pharmaceutical manufacturing industry is still evolving. This is evidenced by the multitude of regulatory guidance documents that advocate the use of statistical process management tools to support the implementation of quality management systems. Quality metrics, such as lot acceptance rate, product quality complaint rate, invalidated out-of-specification rate have been identified by the FDA as being valuable in assessing the overall effectiveness of a company’s’ quality management system. The appropriateness of process capability indices (PCIs) is also being considered as PCIs are a measure of the process’s ability to produce product that complies with specifications. Most individuals jump right to the computation of the PCIs, thereby placing more value on the metric itself than the product and process knowledge obtained through the appropriate evaluation of the manufacturing process. This presentation initiates a discussion of how to appropriately use the information obtained from process capability/process performance assessments.