beginner · metrics
Why p99 and Not the Average?
Why do teams look at p99 latency instead of the average? And when is p99 the wrong number?
Practical scenario
A weekly report shows "average API latency: 120 ms, well within target". Support has been escalating complaints about slow page loads all week.
What it tests
- • Understanding that latency is a distribution, not a value
- • Whether the candidate can also argue against p99
- • Awareness of how traffic volume changes what a percentile means