Determining Proficiency Test Quality

Several things need to be considered when examining the quality of a proficiency test…

1. Artifact Quality and Reliability
2. Credibility of the Reference Laboratory
3. Packaging and Shipping
4. Monitoring for Stress Response of the Artifact
5. Proper Estimation of the Artifact Assigned Value Uncertainty
6. Statistical Methods of Analysis
7. Quality of the Test Report
8. Promptly Delivered Test Report

1. Artifact Quality and Reliability

We select and monitor an artifact, as needed, prior to enlisting it into any of our proficiency tests. The selection process considers the uncertainty attainable by the artifact, shipping stress response, the environment required to use the artifact and packaging requirements. Our on-going monitoring process ensures any unexpected non-reliability can be discovered prior to reports being issued to the participant.

2. Credibility of the Reference Laboratory

In any proficiency test, the conclusions are only as good as the selected reference laboratory. MeasurePT uses accredited laboratories with a proven record of reliable capability with uncertainties considerably smaller than the targeted participants in order to establish the reference value of the artifact, which ensures reliable validation of our participants best measurement capability.

As per the requirements of ILAC G13:2000, Guidelines for the Requirements for the Competence of Providers of Proficiency Testing Schemes, a Collaborator is a body that undertakes subcontracted activities for a proficiency testing scheme provider. MeasurePT subcontracts with and pays for services such as establishing the Artifact Reference Value (calibration) and/or technical review of a particular proficiency test. Please follow the links below for information regarding MeasurePT's collaborators.

3. Packaging and Shipping

After the artifact is metrologically inspected in our quality control laboratory, it is packaged using foam in place packaging, along with any specified monitoring equipment, according to MeasurePT's specific requirements which are designed to minimize any stress response potential. 

4. Monitoring for Stress Response of the Artifact

We use several methods to ensure that any significant change in the value of the artifact is discovered and appropriate actions are taken. Each artifact starts its deployment by being measured at MeasurePT, then sent to the Reference Laboratory for value assignment, returned to MeasurePT and measured again to ensure artifact reliability. Upon a test participation request, the artifact is measured by MeasurePT, again to ensure reliability, packaged with any appropriate monitoring equipment, such as "shock watches" and miniature data-logging "Hygrometer", (these devices provide notification to us of the exposure of the artifact to potentially damaging stress) and sent to the participant for Measurement Proficiency Testing of their laboratory.

MeasurePT Petal Design

The participant completes their measurements and ships the artifact back to MeasurePT where it is inspected and re-measured by the QC Lab to once again ensure the artifacts reliability of use. The artifact is periodically re-measured by the Collaborator and any deviation to previous measurement is compared to MeasurePT's trend data to reconcile any apparent change in value.  Further information is available in the following paper by Jeff Gust, Director of MeasurePT, on innovations in proficiency testing.

This method is referred to as the MeasurePT Petal Design where the Reference Laboratory receives the artifact from the proficiency test provider (identified in the middle or Pivot Laboratory (PL)) and then the measurement design circulates the artifact between the participants or Labs, and back to the Pivot Laboratory.

5. Proper Estimation of the Artifact Assigned Value Uncertainty

We start with the Collaborator's measurement uncertainty and appropriately combine any additional uncertainties due to any apparent change in value as determined by before and after testing performed by MeasurePT and the Collaborator. This ensures that our uncertainty is not understated, which may cause our participants to falsely fail the test. Where applicable, artifact values are trended by MeasurePT to add further confidence in the assigned artifact value.

6. Statistical Methods of Proficiency Determination

All proficiency tests conducted by MeasurePT currently assess the proficiency of the laboratory by use of determining the Normalized Error of the proficiency test.  A laboratory is deemed acceptable if their computation of Normalized Error is within the range of -1.00 to 1.00. Additional statistics are not necessary because of the metrological rigor in determining the reference value and its associated uncertainty by the reference laboratory.

7. Quality of the Test Report

In order to ensure that the Final Report is of the highest quality, MeasurePT delivers a data verification form to each customer before the final report is issued.  The customer reviews all data, and signs and returns the preliminary report if all data has been correctly interpreted, so the final report will be free from errors.

8. Promptly Delivered Test Report

Tired of tracking down your test results prior to your assessment? Due to the unique methods we employ to ensure quality and adequate knowledge of the artifacts value, we can provide you with your report within two weeks after you make your measurements, providing payment is received by MeasurePT.