A mean summarizes the total divided by the count. A median describes the middle of an ordered sample. Percentiles describe a position in that distribution, with conventions that should be stated. Averages can hide a small number of very slow requests.
Variance and spread help describe how consistent observations are. For latency, report the workload, sample size, and relevant tail behavior as well as the mean. Separate queue time from execution time when possible.
Do not mix failed requests into a latency report without explaining how they were handled. Excluding every timeout can make an unreliable service appear faster. Quality, failure rate, and latency should be interpreted together.
Exercise: compare two synthetic latency sets with the same mean but different tails. Add timeouts and decide how to report them.
Check: the report includes sample size, percentile convention, and failure rate rather than a single flattering average.