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The kurtosis is the fourth standardized moment, defined as [] = [()] = [()] ( [()]) =, where μ 4 is the fourth central moment and σ is the standard deviation.Several letters are used in the literature to denote the kurtosis.
The fourth central moment is a measure of the heaviness of the tail of the distribution. Since it is the expectation of a fourth power, the fourth central moment, where defined, is always nonnegative; and except for a point distribution, it is always strictly positive. The fourth central moment of a normal distribution is 3σ 4.
The first central moment μ 1 is 0 (not to be confused with the first raw moment or the expected value μ). The second central moment μ 2 is called the variance, and is usually denoted σ 2, where σ represents the standard deviation. The third and fourth central moments are used to define the standardized moments which are used to define ...
The first cumulant is the mean, the second cumulant is the variance, and the third cumulant is the same as the third central moment. But fourth and higher-order cumulants are not equal to central moments. In some cases theoretical treatments of problems in terms of cumulants are simpler than those using moments.
For any non-negative integer , the plain central moments are: [25] [()] = {()!! Here !! denotes the double factorial, that is, the product of all numbers from to 1 that have the same parity as . The central absolute moments coincide with plain moments for all even orders, but are nonzero for odd orders.
In probability theory and statistics, the Poisson distribution (/ ˈ p w ɑː s ɒ n /) is a discrete probability distribution that expresses the probability of a given number of events occurring in a fixed interval of time if these events occur with a known constant mean rate and independently of the time since the last event. [1]
Inspirational 4th of July quotes “Let us therefore animate and encourage each other, and show the whole world that a Freeman, contending for liberty on his own ground, is superior to any slavish ...
In probability theory and statistics, the exponential distribution or negative exponential distribution is the probability distribution of the distance between events in a Poisson point process, i.e., a process in which events occur continuously and independently at a constant average rate; the distance parameter could be any meaningful mono-dimensional measure of the process, such as time ...