[dastbe]

every statistic is a summary and a lie. p50/p99 metrics are good in the sense that they tell you a number someone actually experienced and they put an upper bound on that experience. they are bad because they won’t tell you is how the experience below that bound looks.

mean and all it’s variants won’t show you a number that someone in your system necessarily experienced, but it will incorporate the entire distribution and show when it has changed.

in the context of efficiency, mean is beneficial because it can be used to measure concurrency in a system via littles law, and will signal changes in your concurrency that a percentile metric won’t necessarily do.