Basic QC Practices
What do you do when you're control is out-of-control? Conventional wisdom is that you repeat the control or try a new one. But that ignores the problem. It doesn't solve anything. Elsa P. Quam BS, MT(ASCP) explains what bad habits we have and what good habits we can adopt to make our laboratory practice better
Dr. Westgard explains how an analytical testing process works to reject the bad runs and keep the good runs. False rejection and error detection are explained. The different kinds of problems (precision , accuracy, etc.) are also described. If you've ever wondered whether there was method to your laboratory madness, this article is for you.
This lesson discusses one of the cornerstones of QC practice. We can no longer take for granted that everyone knows how to build a control chart, plot the control values, and interpret those results correctly. Patricia L. Barry, co-author of Cost-Effective Quality Control: Managing the Quality and Productivity of Analytical Processes, provides a primer on how to construct, use, and interpret the Levey-Jennings chart.
This lesson discusses the math involved with QC practice. Despite the age of computers, we still have to crunch the numbers ourselves sometimes. Dr. Westgard discusses the terms Mean, SD, CV, Control Limits, z-scores and SDI's, explaining what they are, giving the equations, and demonstrating how to calculate them.
Elsa F. Quam, BS, MT(ASCP) is one of our most popular guest essayists. Elsa rightly points out that while we concentrate on the statistics of quality control, we can't forget the selection of the control materials. Important attributes such as the stability, vial to vial variability, assayed versus unassayed, appropriate analyte levels, and pretreatment procedures affect the very success of the control procedure.