Potential use of the scan statistic for quality control in blood product manufacturing

There are minimal standards for the processing of whole blood components, and to apply those standards requires a system of quality assurances. Excessive indications of failures in compliance trigger inspections and other remedial actions, but the demarcation of what is excessive is a critical issue. Issues of low volume in some production facilities, low expected frequency of nonconformance, multiple nonindependent statistical tests, and controlling both the false-positive and false-negative rates all complicate quality assurance procedures. The scan statistic is a statistic that computes the number of events in a moving window throughout the period of risk. Monitoring plans based on scan statistics are developed to estimate the probability that a process that is under control.