The model is based on reported days. For example, the benchmark rate used is 40 reported days or approximately eight calendar weeks. Likewise, the exchange rate recognition period is 40 reported days or approximately eight weeks. In other words, the weekly average of the actual daily rates will be compared to the average benchmark rate for the same week. If the actual exchange rate average exceeds the benchmark average by five percent or more for eight consecutive weeks, a sustained movement in the value of the currency is deemed to have occurred.
Daily rates are too volatile.
A sustained movement is deemed to have occurred when the average rate for each of the eight weeks of the recognition period deviates from the benchmark by more than five percent. In investigations, if a sustained movement has occurred, and the foreign currency has increased in value in relation to the U.S. dollar, continue to use the official rate from the last day of the recognition period for 60 days following the end of the recognition period. On the 61st day, we would return to comparing the actual daily rate to the benchmark rate. Whenever the decline in the value of a foreign currency is so precipitous and large as to reasonably preclude the possibility that it is only fluctuating, use actual daily rates from the start of the recognition period. Susan G. Esserman, Assistant Secretary for Import Administration .