Some values are expressed as 95% or 99% which is 95th and 99th percentile respectively. For example, if the Mean Opinion Score (MOS) 95% is 3 it tells us that at least 5% of all calls have the MOS score 3 or worse. It is better to watch 95% or 99% than average or min/max values because average/min/max do not tell engineers that 5% of all calls are bad.
Below is an example of how the percentile is calculated for the MOS score. Say we have 100 calls where only the last 5 calls have MOS score 3.1, 2.5, 3.2, 1.0, 2.9.
order all MOS calls by the best MOS score to the lowest (4.5, 4.5...3.2, 3.1, 2.9, 2.5, 1.0)
remove first 95% of all calls (3.2, 3.1, 2.9, 2.5, 1.0)
take the first number from the left of the remaining 5% which is 3.2
In this example, the MOS score 95th percentile is 3.2. The average MOS score is 4.4, Min is 1.0 Max is 4.5. As you can see the average/min/max are not useful but the 95th percentile tells us that we have a problem with 5% of all calls.
