The New Dimension to Resolution: Can it be Resolved? Our last blog, Device Resolution and the Impact on Consumer Risk, described why best practices should be followed for conformity assessments rather than drafting individual test protocols and standards. How should manufacturers and calibration laboratories correctly calculate both uncertainty and risk on equipment? Risk, Conformity Assessment, […]
Device Resolution and the Impact on Consumer Risk - Intro If a device's uncertainty has too coarse of a resolution, then you need a device that does not subject the conformance decision to higher risk. This blog will present examples that demonstrate why best practices should be followed for conformity assessments rather than drafting individual […]
TAR versus TUR: Why TAR should RIP ASAP In our last blog, Examining the History of TAR and TUR, we examined several outdated, and to some extent wrong, practices, such as Test Accuracy Ratios (TARs) and requesting NIST traceable calibrations. Remember when they buried the word "DEF"? Maybe we, as metrologists, need to do that […]
Examining the History of TAR and TUR Why examine TAR and TUR? Hasn’t each topic been covered for decades now? When we look at TAR and TUR concepts, we find that many in the metrology community have adopted TUR. Both guidance documents and standards have moved away from TAR. However, when we look at the […]
In the last Back-to-Basics blog, I covered Calibration versus Verification. As I continue to cover basic concepts for beginners, this blog will define measurement uncertainty and examine why it is important. What is Measurement Uncertainty? What measurement uncertainty is not is an error. It is imperative to understand the difference between these two terms as […]
In the last Back-to-Basics blog, I covered Compression and Tension Force Calibration. As I continue to cover basic concepts for beginners, this blog will cover the differences between calibration and verification. What is a Calibration? Let me start by stating that there are several definitions of calibration across multiple standards. My favorite definitions are below. […]
Guide for Understanding Uncertainties on a Morehouse ASTM E74 Calibration Certificate Reporting the Expanded Uncertainty on an ASTM E74 Calibration Certificate of the measurement is a requirement of ISO/IEC 17025 and likely always will be. However, if you look at several different certificates of calibration, their Expanded Uncertainty reported, contributors and reporting methods will vary […]
Load Cell Calibration: What Does “Traceable to NIST” Really Mean? Load cells have various applications across several fields, from verifying the correct amount of stamping press force to testing rocket thrust stands. They are so common that almost everyone owns several in some shape or form, whether they realize it or not. Load cells are […]
Specifying a Tolerance, the Difference Between Percentage of Indicated Value vs % of Full-Scale Output - Intro In looking at various equipment, it seems the force equipment in the test and measurement industry specifically specifies tolerances as a percent of full scale. When determining accuracy or tolerance, several crane scales, tension links, and hand-held force […]
How to Calculate the Resolution of a Load Cell Per Section 4.14 of JCGM 200:2012, Resolution is the “smallest change in a quantity being measured that causes a perceptible change in the corresponding indication.” Over the years, this simple definition has become a topic of confusion in the metrology community. We are hoping to simplify […]
The Importance of Considering Reproducibility in the Measurement Process Uncertainty - Intro Most people in the metrology community will agree that a calibration laboratory's ability to reproduce measurement results belongs in an uncertainty budget. Several Accreditation Bodies require reproducibility to be at least considered as part of a calibration laboratory's Calibration and Measurement Capability (CMC). […]
Why a 4:1 TUR is Not Enough: The Importance of Analyzing the Probability of False Accept Risk Figure 1 Graph Showing Method 5 Acceptance Limits Several organizations and publications reference the use of a 4:1 Test Uncertainty Ratio (TUR). Some standards even reference a TUR requirement greater than or equal to 4:1. The question to […]
