Course Content

11 - How Proficient Are We



External Quality Assessment Schemes (EQAS) enable the laboratory to assess on-going accuracy by comparing its method’s performance to external sources.  In this activity, participants are introduced to standard deviation index (SDI) and z-score and will review a proficiency test (PT) report.

Key Message

  • Proficiency testing (PT) programs provide a way to verify long-term accuracy of a method.
  • SDI is a quick indicator of how well our mean compares to the method peer mean.
  • All PT failures must be investigated and documented by the laboratory.

Self Assessment

Can you: 

  • Recognize the common elements found in a PT report and their significance?
  • Calculate SDI and use that information to assess the accuracy of the method?
  • Recognize that PT results, both acceptable and unacceptable, should be evaluated?