MEASURE FOR MEASURE
Out of Sync
If we’re not on the same page, quality efforts go down the drain
by Jay L. Bucher
Because of deadlines and other time commitments, I’m writing this while Santa is still 10 days away from his yearly trip, so I have the privilege of looking to the future from the past. It’s kind of like looking out the windshield of your car while still being able to glance in the rearview mirror and see what is behind you.
During the holidays, when children everywhere wonder whether they’ll have presents or coal waiting for them on Christmas morning, my thoughts always turn to the concept of good and bad—or, more broadly, to the idea of perception.
President Barack Obama has been in office for a little more than a year, and much of that time has been spent haggling over his job performance. As might be expected, half of the country thinks he’s doing a fine job, while the other half couldn’t disagree more.
The same discord occurs among U.S. legislators, who are occupied by the dilemma of the U.S. healthcare bill. I’m amazed how two people (or political parties) can read the same piece of legislation and form entirely different opinions about what it means.
Then, I realized the same conundrum happens daily in the world of quality.
Two people look at the same standard or regulation and read into it different things. Does this come from their education, background, training or the type of car they drive? No matter the cause, the effect is usually the same—an observation, write-up or Form 483 from the FDA is generated, justified or not, and somebody needs to answer why and how it is going to be fixed.
Based on my experiences in the world of measurement (remember that metrology is the science of measurement), one of the reasons this happens is because either the personnel in charge of the calibration department or the inspector (auditor) doesn’t understand the definition of two basic words—calibration and traceability.
Clearing up calibration
During my first audit as a civilian after an extended military career, I was told that mercury thermometers (as opposed to electronic thermometers) could not be calibrated because they could not be adjusted.
After picking my jaw off the table, I very courteously informed the auditor she was mistaken and tried to explain the real meaning of calibration—the comparison of two measurement devices or systems, one of known uncertainty (your standard) and one of unknown uncertainty (your test equipment). The ability to adjust, align or repair has absolutely nothing to do it.
I showed her a couple references and provided examples. She took a few notes and thanked me for correcting a long-held belief, and my calibration program received a laudable commendation during the out-briefing.
At the time, the quality manager and division vice president were having simulated coronaries because I dared to question an auditor; but they were quick to recover when they realized they also did not know the correct meaning of calibration.
Before I continue, I should point out that it’s never a good idea to argue with an auditor or inspector. In this case, I was not arguing with her; I was helping to educate her on a topic about which she was mistaken, thereby helping to make her a more informed auditor. She thanked me for helping her, and I appreciated that.
I’m not advocating similar actions every time you disagree with an inspector or auditor—quite the contrary. You must have all your references lined up and just cause to challenge them. That’s why you have rebuttals and negotiations to go along with written responses.
Getting back to calibration, at the time of my discussion with the auditor, my thoughts turned to how the definition of calibration was not something I made up at the spur of the moment. In fact, it has been around for at least 5,000 years. The National Conference of Standards Laboratories International offers the following example, which validates calibration.1
One of the earliest records of precise measurement comes from the Egyptians, who studied geometry to assist them in the construction of the pyramids. It is believed that in about 3000 B.C., the Egyptian unit of length came into being. The Royal Egyptian Cubit was decreed to be equal to the length of the forearm from the bent elbow to the tip of the extended middle finger plus the width of the palm of the hand of the pharaoh or king ruling at that time.
The Royal Cubit Master was carved out of a block of granite to endure for all times. Workers building tombs, temples and pyramids were supplied with cubits made of wood or granite. The royal architect or foreman of the construction site was responsible for maintaining and transferring the unit of length to the instruments used by workers, who were required to bring back their cubit sticks at each full moon to be compared to the Royal Cubit Master. Failure to do so was punishable by death.
Though the punishment prescribed was severe, the Egyptians inadvertently had anticipated the spirit of the present day system of legal metrology, standards, traceability and calibration recall. With this standardization and uniformity of length, the Egyptians achieved surprising accuracy. Thousands of workers were engaged in building the Great Pyramid of Giza, which was constructed to stand roughly 756 feet. Through the use of cubit sticks, they were within 4-1/2 inches—an accuracy of 0.05%.
There is one other part of this equation—traceability. According to ISO/IEC Guide 99:2007, traceability is the property of a measurement result whereby the result can be related to a reference through a documented unbroken chain of calibrations, each contributing to the measurement uncertainty.
The note at the end of the definition for metrological traceability defines the expression "traceability to the SI (International System of Units)" as "metrological traceability to a measurement unit of the International System of Units."2
The SI is based on the International System of Quantities. Along with rules for its use, the SI was adopted by the General Conference on Weights and Measures. Test equipment calibration is not traceable to the U.S. National Institute of Standards and Technology (NIST), but to the SI through NIST. All calibration certificates and records should have a statement that declares their calibration is traceable to the SI (if, in fact, their calibration is traceable either through third-party calibration labs or NIST).
Some of you may remember an old English proverb: For want of a nail the shoe was lost; for want of a shoe the horse was lost; for want of a horse the rider was lost; for want of a rider the battle was lost; for want of a battle the kingdom was lost; and all for the want of a horseshoe nail.
The same could be said of a traceability statement—without it, there is no proof calibration took place. If the calibration of your test instrument is not traceable to the SI, then true calibration has not been accomplished, and you might as well prepare yourself for the inevitable observation, write-up or Form 483.
Here’s hoping all of you are on the same page when it comes to traceable calibration in your quality systems, and that our legislators consider basing decisions on objective data with traceability to solid facts.
- Stuart Kleven, Israel Vasquez and David Atkins, "Calibration for Nondestructive Testing," www.asnt.org/publications/materialseval/basics/oct06basics/oct06basics.htm.
- International Organization for Standardization, ISO/IEC Guide 99:2007—International vocabulary of metrology—Basic and general concepts and associated terms (VIM), 2007.
Jay L. Bucher is president of Bucherview Metrology Services in De Forest, WI. He is editor and coauthor of The Metrology Handbook and author of The Quality Calibration Handbook, Paperless Records and Ethics—The Final Frontier. He is a senior member of ASQ, the chair of the Measurement Quality Division and a certified calibration technician.