A Levey-Jennings chart is a graphical tool used in quality control to monitor and analyze data over time. It is named after its creators, Dr. Levey and Dr. Jennings, who developed the chart in the 1950s as a way to detect changes in the performance of medical laboratory instruments.

The chart is a graph with time on the horizontal axis and the results of quality control tests on the vertical axis. The results are plotted as a series of points or dots. A centerline is drawn on the chart to represent the expected or target value for the test. Upper and lower control limits are also drawn on the chart to indicate the acceptable range of variation in the test results.

The chart allows laboratory personnel to track the performance of a test over time and identify trends or shifts in the results. If a test result falls outside the control limits, it suggests that there may be a problem with the test or the instrument, and further investigation is needed. The Levey-Jennings chart is a widely used tool in medical laboratories and other industries that rely on quality control testing.