Click below for a downloadable PDF for help on Levey-Jennings quality control charts. Observe the Evaluating Run Data figure for reject figures and quiz yourself on the problems in each set of charts. Consider the charts a sketch of the data presented next to each set. Compare your thoughts with mine after looking at each chart.
Click here to view the sample L-J charts.
Chart 1: The is a 1 3SD rule failure on run 19. L II. Why? Hard to tell without more data. Could be either INCREASED Random (RE) or Systematic (SE).
Chart 2: There is a 2 2SD on runs 6-7. L I. = SE. And on run 25 an R 4SD. RE. Note R for range and random.
Chart 3: 1 3SD on 17 L II (RE or SE) and 2 2SD on 26 -27 L I SE.
Chart 4: 2 2 SD on runs 24 - 25 -26. L I. SE. Wasn't fixed at run 25!
Chart 5: Okay.
Chart 6: 2 1 3SD failures as well as 2 2SD (OK if you said only one of them) SE.
David Plaut is a chemist and statician in Plano, TX. He welcomes your questions or comments at email@example.com.