Example of a statement of measurement uncertainty for EMC testing (from an EMC test report):
All measurements involve certain levels of uncertainties, especially in the field of EMC. The factors contributing to uncertainties are spectrum analyzer, cable loss, antenna factor calibration, antenna directivity, antenna factor variation with height, antenna phase center variation, antenna factor frequency interpolation, measurement distance variation, site imperfections, mismatch (average), and system repeatability.
Based on NIS 81, "The Treatment of Uncertainty in EMC Measurements", the best estimate of the uncertainty of a radiation emissions measurement at HTW is +4.0 dB.