Dictionary:Kurtosis

{{#category_index:K|kurtosis}} (kur tō’ sis) A measure of the sharpness of a population distribution. If x₁₀, x₂₅, x₇₅, and x₉₀ are the values for which 10, 25, 75, and 90% of the population is smaller, respectively, then

${\text{kurtosis}}={\frac {x_{75}-x_{25}}{2(x_{90}-x_{10})}}$

From the Greek word for "curvature".