quartile

American  

[kwawr-tahyl, -til] / ˈkwɔr taɪl, -tɪl /

noun

1. Statistics. (in a frequency distribution) one of the values of a variable that divides the distribution of the variable into four groups having equal frequencies.

2. Astrology. a quartile aspect.

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adjective

1. Astrology. of or relating to the aspect of two heavenly bodies when their longitudes differ by 90°.

quartile British  

/ ˈkwɔːtaɪl /

noun

1. statistics one of three actual or notional values of a variable dividing its distribution into four groups with equal frequencies

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adjective

1. statistics denoting or relating to a quartile

2. astrology denoting an aspect of two heavenly bodies when their longitudes differ by 90°

3. a quarter part of a distribution

Etymology

Origin of quartile

1500–10; < Medieval Latin quartīlis, equivalent to Latin quart ( us ) fourth + -īlis -ile

Explanation

When statisticians divide things into four equal parts, any one of those parts is called a quartile. You might, for example, hear about a successful school that's in the upper quartile of state test scores. People studying information about how people live — how much money they make, how healthy they are, how much they travel, what their ages are, what TV shows they watch — often separate them into groups for comparison. It's sometimes easier to examine statistics and information when it's divided into quartiles, or fourths. The original use of the word quartile was in astronomy, to mean "ninety degrees apart," from the Latin root word quartus, "fourth."

Example Sentences

Notice that the stock market’s average subsequent return in the lowest quartile is higher than for either the second or third quartiles.

From MarketWatch • Mar. 13, 2026

At funds worth $750 million to $999 million, pay for the top quartile was at least $600,000.

From The Wall Street Journal • Nov. 20, 2025

Humana expects to return to the top quartile for 2027 star ratings, which would boost its 2028 reimbursements, analysts at Oppenheimer & Co said.

From Barron's • Oct. 3, 2025

The study notes that there “continues to be wide variation in financial performance among hospitals, with the bottom quartile showing a net income margin of -5%, compared to +13% for the top quartile.”

From Los Angeles Times • Oct. 9, 2024

This point corresponds to the important value called the probable error, and was designated by Galton as the quartile.

From Species and Varieties, Their Origin by Mutation by Vries, Hugo de