Definition: Average and 90th Percentile

​The average time is the dispatch or response interval time that typifies the set of time intervals that it belongs to (e.g., the month) and is calculated by summing the times of all the intervals in the set and dividing by the number of intervals in the set.

The 90th percentile time is the dispatch or response interval time at which 90 percent of the intervals were faster and 9 percent were slower.