分位数（英语：Quantile），亦称分位点，是指将一个随机变量的概率分布范围分为几个等份的数值点，常用的有中位数、四分位数、百分位数等。

分位数指的就是连续分布函数中的一个点，这个点对应概率p。

In statistics and the theory of probability, quantiles are cutpoints dividing the range of a probability distribution into contiguous intervals with equal probabilities, or dividing the observations in a sample in the same way. There are one fewer quantiles than the number of groups created. Thus quartiles are the three cut points that will divide a dataset into four equal-size groups. Common quantiles have special names: for instance quartile, decile (creating 10 groups: see below for more). The groups created are termed halves, thirds, quarters, etc., though sometimes the terms for the quantile are used for the groups created, rather than for the cut points.