The GUM in Plain English, Part 6 of 7: Coverage Factor: Why k = 2 Sometimes Lies Part 5 combined our nine inputs into a combined standard uncertainty of uc = 0.666 lbf. That is one sigma, and by itself, it is too thin to act on. Figure 11. One sigma catches about 68 %. […]
The GUM in Plain English, Part 5 of 7: Combined Standard Uncertainty: The Catch Called Correlation Parts 3 and 4 sized all nine inputs in our 5000 lbf budget: four Type A pieces earned from data, five Type B pieces built from what we already knew. Now you need one number for the result. You […]
The GUM in Plain English, Part 4 of 7: Type B Uncertainty: The Doubt You Already Know Part 3 earned four numbers by repeating measurements: our Type A pieces, led by a 0.58 lbf single-reading repeatability at 3 degrees of freedom. But not all doubt comes from repeating a measurement. Most of it, in a […]
Part 3 of 7: Type A Uncertainty: The Doubt Your Own Data Hands You In Part 2 we wrote the measurement model and named every input in our 5000 lbf budget. Now we start filling in numbers, beginning with the ones we earn ourselves. Figure 4. Four loadings at 5000 lbf: 5000, 5001, 5000, 5001. […]
The GUM in Plain English, Part 2 of 7: Error vs Uncertainty, and the Exhaust Port in Your Model In Part 1 we agreed that a measurement without an uncertainty is an opinion with a decimal point, and we listed where the doubt in a force lab comes from. Before we can size any of […]
Part 1 of 7: Measurement Uncertainty: An Opinion With a Decimal Point Pull any calibration certificate off the shelf, and you will find a line like U = 1.71 lbf, k = 2.57, approximately 95 % confidence. Most of the people who read that line, including some who sign it, could not tell you where […]
Tell Me Whose Day Was Better Because You Were in It: Showing Appreciation in the Metrology Community In December 1989, United States forces cornered Manuel Noriega inside the Vatican embassy in Panama City. The story everyone repeats is the rock playlist. Van Halen’s “Panama.” The Clash. Guns N’ Roses at volume, aimed at the nunciature […]
The Honest Answer that May Have Cost us a Million Dollars: Why Trustworthy Calibration Services Matter “You can’t handle the truth!” – Colonel Jessup, A Few Good Men Colonel Jessup was wrong about most things, but he was onto something: the truth is not always what people want to hear. Not long ago, a prospective […]
Two Degrees Off: What Mount Erebus Teaches Us About Measurement Bias I recently read 10x Is Easier Than 2x by Dan Sullivan and Dr. Benjamin Hardy, and one story in it made me think about calibration, specifically a paper I wrote three years ago on bias. Before we get to that, here’s more about what […]
Understanding the Normal Distribution The normal distribution, sometimes called the bell curve or Gaussian distribution, is one of the most important concepts in statistics. It describes how values of a variable are spread, and it often appears in nature, science, and everyday life. What is the Normal Distribution? At its core, the normal distribution […]
Load Cell Calibration for Rocket Engine Test Accuracy Load cell calibration for rocket engine thrust accuracy is something anyone making rockets should understand. Rocket engine testing represents one of the most critical phases in aerospace engineering, where precision and reliability are paramount. This article explores the fundamentals of load cell calibration for rocket engine thrust […]
Understanding Compression Load Cell Equations Compression load cells are critical for measuring pushing forces in various applications. Here at Morehouse, we calibrate many tension load cells from various capacities. One of the more essential aspects of these calibrations is ensuring the appropriate adapters are used. Our e-book and other documents speak to the importance of […]
