On Quality Control

Review this quiz and commentary on Levey-Jennings QC charts.

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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 davidplaut@yahoo.com.

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