What does quantile mean?
A quantile is a division point in a probability distribution: it identifies a value below which a chosen proportion of observations falls and above which the remainder falls. Quantiles are commonly written as proportions, so the 0.5 quantile is the median, while the 0.9 quantile is equivalent to the 90th percentile. They are useful for describing and comparing distributions without relying only on their average. For example, a company may examine the 95th quantile of customer waiting times to understand a threshold that most customers do not experience but that can reveal serious delays. The term is also important in finance and risk analysis, where upper quantiles help estimate unusually large or costly outcomes. Although quantiles are often associated with modern statistics, the concept has a long history in the mathematical study of distributions.
nounA quantile is a value that divides a probability distribution into a specified proportion below it and the remaining proportion above it. The median, for example, is the 0.5 quantile, or the 50th percentile.
- A value below which a specified proportion of a probability distribution falls.
- Any of the ordered values that characterize the distribution of a random variable.
"The 90th quantile of the distribution represents a threshold below which 90 percent of the observations fall."
"The median is the 0.5 quantile of the observations."
"Risk analysts estimated the 95th quantile of possible losses before deciding how much capital to hold."
Plural when referring to multiple division points or values in a distribution.
"The analyst calculated the quantiles for each income group."
A quantile turns an entire distribution into a set of useful landmarks: the median is one, and the 90th quantile marks the threshold exceeded by only one-tenth of the data.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does quantile come from?
The word comes through French quantile, from Latin quantus, meaning “how much” or “how great.” Its statistical sense developed in the 19th century from the broader mathematical idea of dividing a distribution into proportional parts. Related English words include quantity, quantify, quantitative, and quantifier, all sharing the Latin root.
How quantile is actually used
This is primarily a statistical and mathematical term. It is commonly used in data analysis, finance, economics, and risk management, often in technical contexts.
Easily confused with quantile
A quantile is a general division point in a probability distribution, while a quartile is specifically one of the four equal groups created by dividing a distribution into quarters.
A percentile expresses a division point as a percentage from 0 to 100, whereas a quantile expresses the same idea as a proportion from 0 to 1.