Why are Averages Misleading?

Measuring the performance of a distributed system is a difficult problem. When picking up a metric to measure performance, Average seems like an easy choice. It is easy to understand and calculate.

However, averages can also be misleading and can give you a false sense of performance.

Let’s look at a sample of 10 latency readings for a website

The average latency for the above values is 4.9 seconds.

You’ve heard that 5 seconds is a good enough latency and your work here is done. But there’s more to it. Let’s plot the above latencies on a graph (the blue line ...