A number indicating an individual's performance level or score in relation to its standing in the distribution of scores of a representative group of individuals. A percentile rank of 95 means that the individual did as well as or better than 95% or the group upon whom the percentile ranks are based. Percentile ranks cannot be arithmetically manipulated due to their varying interval nature.
Patricia Wheeler, Geneva D. Haertel, and Michael Scriven. (1992). Teacher Evaluation Glossary, Kalamazoo, MI: The Evaluation Center, Western Michigan University.