A percentile is the value of a variable below which a certain percent of observations fall. So the 20th percentile is the value (or score) below which 20 percent of the observations may be found. The term percentile and the related term
percentile rankare often used in descriptive statisticsas well as in the reporting of scores from norm-referenced tests. The 25th percentile is also known as the first quartile(Q1); the 50th percentile as the medianor second quartile(Q2); the 75th percentile as the third quartile (Q3).
There is no standard definition of percentile [cite web
accessdate=2007-09-15] [cite web
title=Statistical flaws in Excel
accessdate=2006-03-22] , however all definitions yield similar results when the number of observations is large. One definition, usually given in unsophisticated texts, is that the -th percentile of ordered values is obtained by first calculating the rank , rounding to the nearest integer, and taking the value that corresponds to that rank.
An alternative method, used in many applications, is to use
linear interpolationbetween the two nearest ranks instead of rounding. Specifically, if we have values , , ,..., , ranked from least to greatest, define the percentile corresponding to the -th value as In this way, for example, if the percentile corresponding to the third value is Suppose we now want to calculate the value corresponding to a percentile . If
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percentile — ⇒PERCENTILE, subst. masc. STAT. Synon. de centile. Les percentiles sont les valeurs de la variable qui divisent la population ou la variable continue en 100 groupes égaux en nombre (1 % de la population) (Éduc. 1979). Prononc. :[ ]. Étymol. et… … Encyclopédie Universelle
percentile — per‧cen‧tile [pəˈsentaɪl ǁ pər ] noun [countable] STATISTICS one hundredth of a set of things or people, arranged in order on a scale: • Our employees pay is at the 90th percentile of that offered by similar companies (= it is higher than the pay … Financial and business terms
percentile — [pər sen′tīl΄, pərsent′ l] n. [ PERCENT + ILE] Statistics 1. any of the values in a series dividing the distribution of the individuals in the series into one hundred groups of equal frequency 2. any of these groups adj. of a percentile or… … English World dictionary
percentile — 1889, from PERCENT (Cf. percent) + ILE (Cf. ile) … Etymology dictionary
percentile — ► NOUN Statistics 1) each of 100 equal groups into which a population can be divided according to the distribution of values of a particular variable. 2) each of the 99 intermediate values of a variable which divide a frequency distribution into… … English terms dictionary
Percentile — The percentage of individuals in a group who have achieved a certain quantity (such as height, weight, and head circumference) or developmental milestone (such as "walking well" the 50th percentile for which is12 months of age). * * *… … Medical dictionary
percentile — UK [pə(r)ˈsentaɪl] / US [pərˈsenˌtaɪl] noun [countable] Word forms percentile : singular percentile plural percentiles one of the 100 equal groups that a large number of people or things are divided into for comparing something such as test… … English dictionary
percentile — /peuhr sen tuyl, til/, Statistics. n. 1. one of the values of a variable that divides the distribution of the variable into 100 groups having equal frequencies: Ninety percent of the values lie at or below the ninetieth percentile, ten percent… … Universalium
percentile — per·cen·tì·le s.m. TS stat. 1. → centile 2. dato o valore che divide una serie ordinata in modo non decrescente dimodoché ogni altro dato o valore a esso inferiore rappresenti una determinata percentuale; anche agg.: dato percentile | estens.,… … Dizionario italiano
percentile — /pəˈsɛntaɪl / (say puh sentuyl) Statistics –noun 1. one of the values of a variable which divides the distribution of the variable into 100 groups having equal frequencies. Thus, there are 100 percentiles: the first, second, etc., percentile.… … Australian English dictionary