Measuring
Typical vs bad day: why we report the 90th percentile
Why every Imperibuild report shows two numbers, and why neither of them is an average.
13 October 2026 · 5 min read · Imperibuild
The typical trip
Sort every sampled trip from quickest to slowest and take the middle one. That is the median, our typical trip. Half your days will be quicker, half slower.
The bad day trip
Take the trip that nine in ten came in under. That is the 90th percentile. One working day in ten, roughly two a month, will be slower than this.
Why not the average
An average is pulled up by one terrible day and down by one empty road. The median describes an ordinary day better, and the 90th percentile describes the day you should plan around.
Reading the gap
A small gap between the two means a predictable trip. A large gap means you need slack in your mornings, whatever the typical time says.
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