Kurtosis Formula Example. The moment coefficient of kurtosis of a data set is computed almost the same way as the coefficient of skewness. For a very large sample very high n the differences between and among n 1 n n 1 n 2 and n 3 are becoming negligible and the sample kurtosis formula approximately equals.
Skr 1 n n i 1 xi x 4 s4 s k r 1 n i 1 n x i x 4 s 4. Where is the mean s is the standard deviation and n is the number of data points. Lastly a negative excess kurtosis represents a platykurtic distribution.
For a very large sample very high n the differences between and among n 1 n n 1 n 2 and n 3 are becoming negligible and the sample kurtosis formula approximately equals.
A normal curve has a value of 3 a leptokurtic has beta 2 greater than 3 and platykurtic has beta 2 less then 3. Proc means data test kurtosis vardef n. 1987 1987 1991 1992 1992 1992 1992 1993 1994 1994 1995. Kurtosis is a descriptive statistic that is not as well known as other descriptive statistics such as the mean and standard deviation descriptive statistics give some sort of summary information about a data set or distribution.
