Percentile

Percentiles rank rather than measure. If a video lands in the top 10% of your channel's uploads, nine in ten of your other videos performed worse on whatever metric was used, which tells you nothing about how it compares to anyone else's. The set is everything. A top-decile video on a small channel and a top-decile video on a large one describe entirely different results. The usual error is reading a percentile as a percentage, so 'top 5%' gets heard as '5% of something' when it is a rank position.