Your ISO 17025 accredited source for Calibration, Certification and Process Control Instruments
All calibrations are traceable to National Institute of Science and Technology (NIST) and comply with ISO standards. Advanced Technical Services offers very competitive pricing, certificates that include full data for each item calibrated, and an electronic recall system so your equipment is never out of calibration. We also have a link so you can complete an on-line customer survey and let us know how we're doing. We take your feedback very seriously and continually make improvements based on your suggestions. 
Please read the Decision Rule below as applied to accredited calibrations by ATS.

The following applies to ACCREDITED CALIBRATION CERTIFICATES only:  


In accordance with ISO/IEC 17025(E), accredited calibration certificates will utilize the “Pass/Fail Guard-Band Method” in reference to measurement uncertainty, effective 02/01/2019. When requesting a statement of conformity to a specification or standard for either tests or calibration, ATS will employ the Pass/Fail Guard-Band Method as its decision rule.  

What is Pass/Fail Guard-Banding?

Pass/Fail Guard-Banding is a statistical method used to eliminate false acceptance test results. When making a statement of conformity, risk based upon false acceptance must be taken into consideration. In order to eliminate false acceptance, the upper and lower limits of any test result will be Guard-Banded against the 95% expanded measurement uncertainty, effectively reducing the upper and lower tolerance limits to create upper and lower acceptance limits.  

In the graphic below you will see horizontal lines representing the nominal value (Blue Line), upper and lower tolerance limits (Red Line), and upper and lower acceptance limits (Green Line) as well as three vertical lines demonstrating measured values (Yellow Circle) with a representation of the 95% expanded uncertainty.  




































Scenario A (PASS)
The measured value is within the upper tolerance limit and upper acceptance limit, as is the attributed 95% expanded uncertainty. This would be considered an “in tolerance” test result because there is no risk of false acceptance.

Scenario B (FAIL)
The measured value is within the upper tolerance limit however it exceeds the attributed 95% expanded uncertainty of the upper tolerance limit. This measurement has a risk of false acceptance because the measured value adjusted by the 95% expanded uncertainty is greater than the upper tolerance limit. This would be considered an “out of tolerance” test result for purposes of this method. Even though the measured value falls inside of the upper tolerance limit, we cannot ensure zero risk of false acceptance due to the expanded uncertainty.  

Scenario C (FAIL)
The measured value exceeds the upper tolerance limit which signifies an out of tolerance test result with no application for the Guard-Band due to the decision rule. 


For any questions regarding Advanced Technical Services’ Pass/Fail Guard-Band Decision Rule and how it may or may not impact you, please feel free to reach out to discuss this further.