Kurtosis is defined as a normalized form of the fourth central moment μ_4 of a distribution. There are several flavors of kurtosis, the most commonly encountered variety of which is normally termed simply "the" kurtosis and is denoted β_2 (Pearson's notation, p. 928) or α_4 (Kenney and Keeping 1951, p. 27, pp. 99-102). The kurtosis of a theoretical distribution is defined by β_2 congruent μ_4/μ_2^2, where μ_i denotes the ith central moment (and in particular, μ_2 is the variance). This form is implemented in the Wolfram Language as Kurtosis[dist].

central moment | excess | k-statistic | kurtosis excess | mean | skewness | standard deviation