Kurtosis

Kurtosis is a measure of the thickness of the tails of a statistical distribution and the sharpness of its peak. Kurtosis is also called the fourth moment about the mean and is one of the two most common statistics used to describe the shape of a distribution (the other is skewness).

There are three types of kurtosis: mesokurtosis, platykurtosis, and leptokurtosis. Many times, these are referred to as zero, negative, and positive kurtosis, respectively. The positive and negative descriptors refer to whether the peak of the distribution is ‘sharper’ or higher than a normal distribution or if the peak is ‘flatter’ or lower than the normal distribution.

Kurtosis statistics compare the distribution under study with the normal distribution. A distribution that [Page 581]resembles the normal distribution in ...