Glossary term
Percentile
The value below which a given percentage of the data falls.
Visual intuition
sort first
2
4
middle seat
100
Median = the value in the middle position
Percentiles are seats in the sorted line-up: the 50th percentile is the middle seat — the median.
Example
If 90% of test takers scored below 82 points, then 82 is the 90th percentile; the is simply the 50th percentile.
How It Works
Sort the whole group and count seats. If a baby's weight is at the 70th percentile, 70% of babies weigh less — a percentile says where a value sits in the ordered crowd, not how good or bad it is in absolute terms. Percentiles survive and outliers, which is why growth charts, test scores, and income tables lean on them.
