The convention for presenting a result: the expanded uncertainty is rounded to at most two significant digits, and the measured value is rounded to the same decimal place. A computed U of 0.003471 V becomes 0.0035 V and the value 1.000237 V becomes 1.0002 V. Rounding the uncertainty up rather than to the nearest digit keeps the statement conservative, while ten digits on a cert signal that nobody thought about what they mean.
Cert shows 1.000237 V plus or minus 0.0035, round the value to four decimals so the significant digits match.
Also heard as
- significant figures
- sig figs
Related terms
Measurement result
The reported value of a measurand together with its uncertainty, the full answer rather than just a number.
Expanded uncertainty
Combined standard uncertainty multiplied by a coverage factor to give an interval with a stated coverage probability.
Calibration certificate
The document reporting a calibration's results, uncertainties, conditions and traceability for one specific item.