“Uncertainty” is a statistic API is required to report for any international labs using our programs. It is the statistical uncertainty of the participant mean, which theoretically provides a range where the “true” mean would be found. It is calculated based on the standard deviation of the dataset and the number of participants’ results included in the dataset. The more participant results are included in a mean, and the lower the standard deviation, the smaller the uncertainty of the mean is.
The formula to calculate the uncertainty of a participant mean is:
1.25 x Standard Deviation
Square Root (number of labs)
More information on uncertainty statistics in proficiency testing is available in the Eurachem guide, "Selection, Use and Interpretation of Proficiency Testing (PT) Schemes by Laboratories."
Note that not all statistics presented in our Participant Data Summary are used to assess performance. CLIA requires a minimum of 10 participants for a peer group to be used for grading. In addition, 80% participant consensus is required (95% for Immunohematology) for a peer group to be used for grading. These two requirements ensure that there is high confidence in the means used for grading results. Please refer to your comparative evaluation for the specific comparison group used to grade your results.
If you have any questions about your results or grading and/or would like further assistance, please contact Technical Support at TechSupport@api-pt.com or 800-333-0958.