Percentiles

Percentiles are used in statistics as a way of determining rank or order in relation to other points in a distribution of numbers or scores. A percentile is a value below the point where a particular percent of scores or observations falls.

For example, the 25th percentile is the number that 25% of the scores are below. Percentile rank is the percent of scores in a distribution which are lower. So someone having a percentile rank of 95% on a test means that 95% of the test takers' scores were lower than theirs.