The range around a result that is claimed to hold the measurand's value with a stated probability. In the classic propagation method it is simply y ± U, symmetric about the result. With Monte Carlo evaluation the interval is read from percentiles of the simulated output distribution, and it can be asymmetric when the model is nonlinear or an input distribution is skewed.
Monte Carlo gives an asymmetric coverage interval, minus 0.8 to plus 1.3, so we can't just quote plus or minus.
Related terms
Expanded uncertainty
Combined standard uncertainty multiplied by a coverage factor to give an interval with a stated coverage probability.
Coverage probability
The probability that the coverage interval contains the measurand's value, usually stated as 95 percent.
Monte Carlo method
Propagating uncertainty by random sampling of input distributions through the measurement model, many thousands of times.
Coverage factor
The multiplier applied to combined standard uncertainty to obtain expanded uncertainty, usually k = 2.