A measurement is produced by a method, an instrument, and a set of conditions. Each can contribute to uncertainty about the quantity being reported. Writing more decimal places does not remove those limitations.
Distinguish a repeated reading from a justified claim about accuracy. Closely grouped readings can still share a systematic offset. A statement of uncertainty needs to reflect the measurement process, not only the spread of a few numbers.
When reading a result, look for an explanation of its limits and how they were assessed. If the difference between two results is small compared with those limits, a confident conclusion may need more evidence. Uncertainty helps determine what the observation can reasonably support.
- Look for the stated measurement limits.
- Separate repeatability from accuracy.
- Compare differences with the uncertainty of the results.
Bring the idea into a day.
Imagine reporting an estimated travel duration as a range. The interval explains ordinary variation that a single exact minute would conceal.
Another angle on the story.
Change one part of the setup and notice what follows. A small, described comparison can make an abstract mechanism easier to reason about.
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NIST: the International System of Units NIST: statistical engineering
