The Levey Jennings QC (Quality Control) chart is a graphical representation of data that is used to monitor the quality of a process over time. It is a statistical tool that is widely used in clinical laboratories to monitor and evaluate the performance of laboratory tests.

The chart consists of a graph with two axes, one representing the test results and the other representing time. The data is plotted as individual points, and a mean value and control limits are added to the chart. The mean value is calculated as the average of all the test results over a specified time period. The control limits are calculated as the mean value plus or minus a certain number of standard deviations (usually two or three).

The chart is used to interpret the data and identify any issues that may be affecting the performance of the process. It is an essential tool for quality assurance and helps to ensure that laboratory tests are accurate and reliable. The Levey Jennings chart is also used to comply with regulatory requirements and accreditation standards, such as those set by the Clinical and Laboratory Standards Institute (CLSI) and the College of American Pathologists (CAP).