I have a problem in which I have six sets of results obtained in sequence from the same chemical test procedure over a period of four months. I know an event occurred during the completion of the sequences of results set. This event may have occurred between results sets 4 and 5, since it appears to have have caused a upward shift in the average of the latter results when compared to the earlier sets. If I treat all results sets independently (number of values, n, per set is between 6-10) can I analyze these sets with an appropriate statistical test, such as ANACOVA, to predict where the event occurred? If not, is there an appropriate mathematical test which would be used to predict where the event occurred? In this case, the event is a certainty, its actual time of occurrence is uncertain.