Measurement Uncertainty Forum
Resolution - Why is it part of the budget of uncertainty?
Ray, The final part of your question is an interesting one and maybe I can shed some light/thought. Consideration of the accuracy or the long-term behavior of an item may not need to be considered if you are calibrating an item on a one time shot say for instance the caliper from Jim's example above. 220.127.116.11 note of ISO-17025:2005 states this as well. Why not consider this? The primary reason is that you may not know this behavior over time. Or in the case of calibration labs may not know this behavior. However, ANSI Z540-1 states that the organization has to statistically analyze the probability of their equipment maintaining some behavior. So, this means that for my own equipment, I may want to track this behavior over a period of time. This is sometimes referred to as a MAP (Measurement Assurance Program). The beauty about this is that if you are tracking an item's long-term behavior, isn't this a statical analysis? You bet. Now this value could be analyzed in your uncertainty budget as a Type A contributor, instead of a Type B with a conservative "accuracy" contribution. Food for thought. I hope this helps. Brent