Adrian Cockcroft's session from Monitorama PDX 2023. Response times for real world systems form complex long tail distributions. The structure and behavior of your system will be visible in the responses, yet the mean and percentile measurements hide this structure, This talk will show how the structure can be measured and analyzed so that you can figure out a useful model of your system, understand when it is working well or about to collapse, what is driving the long tail of latencies, and come up with better service level agreements. The talk introduces a statistical concept called Finite Mixed Models without getting into the greek equations, and shows how to explore this data using R. Looking at response times this way is a far, far better thing that I do, than I have ever done before.