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On the other hand, positive excess kurtosis signifies a leptokurtic distribution. The Laplace distribution, for example, has tails that decay more slowly than a Gaussian, resulting in more outliers. To simplify comparison with the normal distribution, excess kurtosis is calculated as Pearson’s kurtosis minus 3.
The most extreme case of a fat tail is given by a distribution whose tail decays like a power law. A variety of Cauchy distributions for various location and scale parameters. Cauchy distributions are examples of fat-tailed distributions. That is, if the complementary cumulative distribution of a random variable X can be expressed as [citation ...
The Cauchy distribution, an example of a distribution which does not have an expected value or a variance. In physics it is usually called a Lorentzian profile, and is associated with many processes, including resonance energy distribution, impact and natural spectral line broadening and quadratic stark line broadening.
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The t distribution is often used as an alternative to the normal distribution as a model for data, which often has heavier tails than the normal distribution allows for; see e.g. Lange et al. [14] The classical approach was to identify outliers (e.g., using Grubbs's test) and exclude or downweight them in some way.
An example of a geometric distribution arises from rolling a six-sided die until a "1" appears. Each roll is independent with a 1 / 6 {\displaystyle 1/6} chance of success. The number of rolls needed follows a geometric distribution with p = 1 / 6 {\displaystyle p=1/6} .
For example, it’s clear that pulling back from America’s good works across the globe in the name of cutting a small fraction of its annual spending will cost the U.S. more in the long term and ...
(Equivalently, as in the next section, excess kurtosis is the fourth cumulant divided by the square of the second cumulant.) [4] [5] If a distribution has heavy tails, the kurtosis will be high (sometimes called leptokurtic); conversely, light-tailed distributions (for example, bounded distributions such as the uniform) have low kurtosis ...