The prediction uncertainty

Participating time laboratories provide the evaluation for the prediction uncertainty of [UTCUTC(k)] within the framework of Calibration and Measurement Capabilities (CMCs) and CCTF key comparisons for the key comparison database (KCDB). The time interval for declaring the prediction uncertainty is 20 days and the declared values show a large variation; from 20 ns to 200 ns. A study was initiated as a result of this large variation among the declared values to determine reasonable values for the prediction uncertainty of [UTCUTC(k)] depending on the clock used and the time transfer method. The laboratories should exercise caution when evaluating the prediction uncertainty and to avoid misunderstandings due to the deviation between the values of [UTC-UTC(k)] over 20 days.