Degrees of freedom for type A uncertainties are the degrees of freedom for the respective standard deviations. Degrees of freedom for Type B evaluations may be available from published reports or calibration certificates. Special cases where the standard deviation must be estimated from fragmentary data or scientific judgment are assumed to have infinite degrees of freedom; for example,
Worst-case estimate based on a robustness study or other evidence
Estimate based on an assumed distribution of possible errors
Type B uncertainty component for which degrees of freedom are not documented
Repeatability degrees of freedom would be n - 1 where n is the number of samples taken.