Course Content


5 - It Begins with the Right Chart



Using the QC tool, L-J Chart, one can visually inspect a quantitative method’s current accuracy and precision to quickly assess if a change is occurring within the system.  In this activity, participants learn how to correctly create this tool, how to visually assess it, and how to avoid pitfalls commonly encountered with its set-up.

Key Message

  • One of the most widely used tools with QC is the L-J chart.  This tool allows one to visually assess for a change in a method’s current performance.
  • When L-J charts are regularly examined, a small change may be recognized long before a QC rule violation occurs.
  • If the assigned values used on the chart do not reflect the observed values of the current performance, then the QC rules are unable to function properly to detect errors.  The data will no longer appear normally distributed.

Self Assessment

Can you: 

  • Create a properly prepared L-J chart?
  • Visually assess a chart to see if there has been a change in the method’s performance?
  • Recognize common pitfalls when the assigned values do not equal the observed values of a stable system?