1325 / 1609
Definition of Uncertainty: Types of Uncertainty
Expanded uncertainty
is the standard uncertainty multiplied by a coverage factor, k,
such that the statement of the expanded uncertainty gives a higher probability that the
correct value lies within the range of the stated uncertainty.
Often the expanded uncertainty is given the symbol U such that
U = k u
Accuracy and Uncertainty Considerations in Modern Radiation Oncology,
The Modern Technology of Radiation Oncology, J. Van Dyk, 2013
Generally
k
> 1
.
For
k
equal to 1, 2, or 3, there is approximately a 67%, 95%, or 99% probability,
respectively, that
the true value
lies between
±
U of the measured mean value
.
Often we will see uncertainties quoted, for example, “at the
k
2 level” or “with
k
= 2”.