Performance-Driven Quality Control is the process of selecting QC rules and strategies to alert laboratory staff to changes in method performance that may cause patient or proficiency-testing samples to exceed defined quality specifications. By driving your QC process to meet a performance specification, you can reduce the number of times your QC system "cries wolf" when methods operate within acceptable parameters, and maximize the chances that a significant error will be detected quickly. This book is intended to be a clear and simple guide suitable for students and experienced laboratory professionals, and will help you understand the information conveyed by statistical data, so that you can make appropriate decisions and take appropriate action. The text examines relevant theory and includes sections on "hidden hazards" that will alert you to potential discrepancies between theory and application. Worksheets (which aspire to move concepts such as Total Error and Critical Systematic Error from theoretical constructs to practical tools) can be used to assess method performance and investigate potential problems in your laboratories.